Add missing help text for rev-parse's --verify option

Change-Id: I3345f52e0c2a555e4c5edb7effe4be4af4cca10a
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit.pgm/resources/org/eclipse/jgit/pgm/internal/CLIText.properties

@@ -265,6 +265,9 @@ usage_RepositoryToReceiveInto=Repository to receive into
 usage_RevList=List commit objects in reverse chronological order
 usage_RevParse=Pick out and massage parameters
 usage_RevParseAll=Show all refs found in refs/
+usage_RevParseVerify=Verify that exactly one parameter is provided, and that it can be turned into \
+a raw 20-byte SHA-1 that can be used to access the object database. If so, emit it to the standard \
+output; otherwise, error out.
 usage_S3Bucket=S3 bucket name
 usage_S3Expiration=Authorization validity in seconds, default 60 sec
 usage_S3Region=S3 region (us-east-1 | us-west-1 | us-west-2 | eu-west-1 |\