update gitmessage

src/.gitmessage

@@ -1,7 +1,31 @@
-# [Add/Fix/Remove/Update/Refactor/Document] [issue #id] [summary]
+
+# ^ [issue #id] [Add/Fix/Remove/Update/Refactor/Document] [summary] ^
 
 # Why is it necessary? (Bug fix, feature, improvements?)
 
 # How does the change address the issue?
 
 # What side effects does this change have?
+
+# Rationale: 
+# Capitalized, short (50 chars or less) summary
+# More detailed explanatory text, if necessary.  Wrap it to about 72
+# characters or so.  In some contexts, the first line is treated as the
+# subject of an email and the rest of the text as the body.  The blank
+# line separating the summary from the body is critical (unless you omit
+# the body entirely); tools like rebase can get confused if you run the
+# two together.
+# 
+# Write your commit message in the imperative: "Fix bug" and not "Fixed bug"
+# or "Fixes bug."  This convention matches up with commit messages generated
+# by commands like git merge and git revert.
+# 
+# Further paragraphs come after blank lines.
+# 
+# - Bullet points are okay, too
+# 
+# - Typically a hyphen or asterisk is used for the bullet, followed by a
+#   single space, with blank lines in between, but conventions vary here
+# 
+# - Use a hanging indent
+# Read more @ https://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html