git-log: show branch graph (#2587)

pages/common/git-log.md

@@ -18,7 +18,11 @@
 
 `git log --stat`
 
-- Show all commits, tags and branches for the entire repo in a graph format:
+- Show a graph of commits in the current branch:
+
+`git log --graph`
+
+- Show a graph of all commits, tags and branches in the entire repo:
 
 `git log --oneline --decorate --all --graph`