Add CONTRIBUTING.md

.gitignore

@@ -2,7 +2,8 @@
 !*/
 
 !.gitignore
+!CONTRIBUTING.md
+!README.md
 !doc/signify.txt
 !plugin/signify.vim
-!README.md
 !signify.png

CONTRIBUTING.md

@@ -0,0 +1,27 @@
+CONTRIBUTING
+============
+
+If you intend to contribute to this project, please keep some simple rules in
+mind:
+
+    - the short commit message shouldn't be longer than 50 characters
+    - the short commit message should start with an uppercase character
+    - use the imperative for the short commit message
+    - don't finish the short commit message with a '.'
+    - don't use github-specific syntax to close an issue (I'll do that, when
+      merging into master)
+    - it's always a good idea to have a look at 'git log' to get an idea how to
+      format one's own commits
+    - if you have questions about a certain patch or feature requests, just open
+      a Github issue
+
+Examples
+--------
+
+```
+Bad:  "fixed loop to start from 0 instead of 1"
+Good: "Avoid off-by-one issue in skiplist loop"
+
+Bad:  "fixed typo"
+Good: "Docs: typo"
+```