README: warning about obsoleted master branch

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
diff --git a/README.md b/README.md
index df57b1b..34488e6 100644
--- a/README.md
+++ b/README.md
@@ -1,130 +1,40 @@
-# File system notifications for Go
+# WARNING
 
-[![GoDoc](https://godoc.org/github.com/fsnotify/fsnotify?status.svg)](https://godoc.org/github.com/fsnotify/fsnotify) [![Go Report Card](https://goreportcard.com/badge/github.com/fsnotify/fsnotify)](https://goreportcard.com/report/github.com/fsnotify/fsnotify)
+If you are reading this, you use `master` branch of this repository,
+which is wrong.
 
-fsnotify utilizes [golang.org/x/sys](https://godoc.org/golang.org/x/sys) rather than `syscall` from the standard library. Ensure you have the latest version installed by running:
+This branch
+ - should not be used;
+ - is not maintained;
+ - is not supported;
+ - will be removed soon.
 
-```console
-go get -u golang.org/x/sys/...
+You should switch to using the default branch instead.
+
+## Using git
+
+Here's how to switch your existing local copy of this repository from `master`
+to `main` (assuming the remote name is `origin`):
+
+```
+git branch -m master main
+git fetch origin
+git branch -u origin/main main
+git remote set-head origin -a
 ```
 
-Cross platform: Windows, Linux, BSD and macOS.
+In addition to the above, if you want to remove the leftover `origin/master`
+remote branch (NOTE this also removes all other remote branches that no longer
+exist in `origin`):
 
-| Adapter               | OS                               | Status                                                                                                                          |
-| --------------------- | -------------------------------- | ------------------------------------------------------------------------------------------------------------------------------- |
-| inotify               | Linux 2.6.27 or later, Android\* | Supported |
-| kqueue                | BSD, macOS, iOS\*                | Supported |
-| ReadDirectoryChangesW | Windows                          | Supported |
-| FSEvents              | macOS                            | [Planned](https://github.com/fsnotify/fsnotify/issues/11)                                                                       |
-| FEN                   | Solaris 11                       | [In Progress](https://github.com/fsnotify/fsnotify/issues/12)                                                                   |
-| fanotify              | Linux 2.6.37+                    | [Planned](https://github.com/fsnotify/fsnotify/issues/114)                                                                      |
-| USN Journals          | Windows                          | [Maybe](https://github.com/fsnotify/fsnotify/issues/53)                                                                         |
-| Polling               | *All*                            | [Maybe](https://github.com/fsnotify/fsnotify/issues/9)                                                                          |
-
-\* Android and iOS are untested.
-
-Please see [the documentation](https://godoc.org/github.com/fsnotify/fsnotify) and consult the [FAQ](#faq) for usage information.
-
-## API stability
-
-fsnotify is a fork of [howeyc/fsnotify](https://godoc.org/github.com/howeyc/fsnotify) with a new API as of v1.0. The API is based on [this design document](http://goo.gl/MrYxyA). 
-
-All [releases](https://github.com/fsnotify/fsnotify/releases) are tagged based on [Semantic Versioning](http://semver.org/). Further API changes are [planned](https://github.com/fsnotify/fsnotify/milestones), and will be tagged with a new major revision number.
-
-Go 1.6 supports dependencies located in the `vendor/` folder. Unless you are creating a library, it is recommended that you copy fsnotify into `vendor/github.com/fsnotify/fsnotify` within your project, and likewise for `golang.org/x/sys`.
-
-## Usage
-
-```go
-package main
-
-import (
-	"log"
-
-	"github.com/fsnotify/fsnotify"
-)
-
-func main() {
-	watcher, err := fsnotify.NewWatcher()
-	if err != nil {
-		log.Fatal(err)
-	}
-	defer watcher.Close()
-
-	done := make(chan bool)
-	go func() {
-		for {
-			select {
-			case event, ok := <-watcher.Events:
-				if !ok {
-					return
-				}
-				log.Println("event:", event)
-				if event.Op&fsnotify.Write == fsnotify.Write {
-					log.Println("modified file:", event.Name)
-				}
-			case err, ok := <-watcher.Errors:
-				if !ok {
-					return
-				}
-				log.Println("error:", err)
-			}
-		}
-	}()
-
-	err = watcher.Add("/tmp/foo")
-	if err != nil {
-		log.Fatal(err)
-	}
-	<-done
-}
+```
+git remote prune origin
 ```
 
-## Contributing
+## Background
 
-Please refer to [CONTRIBUTING][] before opening an issue or pull request.
+The `master` branch was renamed to `main`, causing an issue with
+Yocto/OpenEmbedded's meta-virtualization layer, which explicitly refers
+to `master` branch of this repository (see #426).
 
-## Example
-
-See [example_test.go](https://github.com/fsnotify/fsnotify/blob/master/example_test.go).
-
-## FAQ
-
-**When a file is moved to another directory is it still being watched?**
-
-No (it shouldn't be, unless you are watching where it was moved to).
-
-**When I watch a directory, are all subdirectories watched as well?**
-
-No, you must add watches for any directory you want to watch (a recursive watcher is on the roadmap [#18][]).
-
-**Do I have to watch the Error and Event channels in a separate goroutine?**
-
-As of now, yes. Looking into making this single-thread friendly (see [howeyc #7][#7])
-
-**Why am I receiving multiple events for the same file on OS X?**
-
-Spotlight indexing on OS X can result in multiple events (see [howeyc #62][#62]). A temporary workaround is to add your folder(s) to the *Spotlight Privacy settings* until we have a native FSEvents implementation (see [#11][]).
-
-**How many files can be watched at once?**
-
-There are OS-specific limits as to how many watches can be created:
-* Linux: /proc/sys/fs/inotify/max_user_watches contains the limit, reaching this limit results in a "no space left on device" error.
-* BSD / OSX: sysctl variables "kern.maxfiles" and "kern.maxfilesperproc", reaching these limits results in a "too many open files" error.
-
-**Why don't notifications work with NFS filesystems or filesystem in userspace (FUSE)?**
-
-fsnotify requires support from underlying OS to work. The current NFS protocol does not provide network level support for file notifications.
-
-[#62]: https://github.com/howeyc/fsnotify/issues/62
-[#18]: https://github.com/fsnotify/fsnotify/issues/18
-[#11]: https://github.com/fsnotify/fsnotify/issues/11
-[#7]: https://github.com/howeyc/fsnotify/issues/7
-
-[contributing]: https://github.com/fsnotify/fsnotify/blob/master/CONTRIBUTING.md
-
-## Related Projects
-
-* [notify](https://github.com/rjeczalik/notify)
-* [fsevents](https://github.com/fsnotify/fsevents)
-
+This temporary branch is created to alleviate the Yocto/OE issue.