Update and explicitly mention "Javadoc" on README

So that Ctrl-F for "javadoc" works.

Related to discussion in #7600.

Fixes #7601

RELNOTES=n/a
PiperOrigin-RevId: 712546871

Author: vorburger

README.md

@@ -74,8 +74,8 @@ Snapshots of Guava built from the `master` branch are available through Maven
 using version `HEAD-jre-SNAPSHOT`, or `HEAD-android-SNAPSHOT` for the Android
 flavor.
 
--   Snapshot API Docs: [guava][guava-snapshot-api-docs]
--   Snapshot API Diffs: [guava][guava-snapshot-api-diffs]
+[Snapshot API Javadoc][guava-snapshot-api-docs] as well as
+[Snapshot API Diffs][guava-snapshot-api-diffs] are also available.
 
 ## Learn about Guava