Add a package-level documentation comment

bluekeyes · bluekeyes · commit ef3359a9693a · 2019-04-14T19:44:06.000-07:00
diff --git a/gitdiff/parser.go b/gitdiff/parser.go
@@ -1,3 +1,6 @@
+// Package gitdiff parses and applies patches generated by Git. It supports
+// line-oriented text patches, binary patches, and can also parse standard
+// unified diffs generated by other tools.
 package gitdiff
 
 import (
