Prepare 3.0-alpha-1 release

gradle.properties

diff --git a/gradle.properties b/gradle.properties
index c53130c..42b9e22 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -1,5 +1,5 @@
 GROUP=com.squareup.leakcanary
-VERSION_NAME=3.0-SNAPSHOT
+VERSION_NAME=3.0-alpha-1
 
 POM_DESCRIPTION=LeakCanary
 POM_INCEPTION_YEAR=2015

mkdocs.yml

diff --git a/mkdocs.yml b/mkdocs.yml
index cd064ec..1843564 100644
--- a/mkdocs.yml
+++ b/mkdocs.yml
@@ -1,7 +1,7 @@
 extra:
   leak_canary:
-    release: '2.11'
-    next_release: '3.0'
+    release: '3.0-alpha-1'
+    next_release: '3.0-alpha-2'
   social:
     - icon: fontawesome/brands/github-alt
       link: https://square.github.io/