REAMDE: Mention that gitlab's 'download' button doesn't work.
This is because the `git archive` command doesn't preserve submodules.
Note that currently there is no support for disabling the 'download' button
in gitlab (https://gitlab.com/gitlab-org/gitlab/-/issues/17032).
Fixes issue #1158.
diff --git a/README b/README
index 7a8a2dc..8560107 100644
--- a/README
+++ b/README
@@ -16,7 +16,9 @@
file `docs/LICENSE.TXT` for the available licenses.
For using FreeType's git repository instead of a distribution bundle,
-please read file `README.git`.
+please read file `README.git`. Note that you have to actually clone
+the repository; using a snapshot will not work (in other words, don't
+use gitlab's 'Download' button).
The FreeType 2 API reference is located in directory `docs/reference`;
use the file `index.html` as the top entry point. [Please note that
