adjust commit template

- remove contradicting instructions to keep subject to one line and at
  the same time wrap at column 72
- git doesn't seem to remove the extra empty line after the subject any
  more, so just insert it and don't be so explict about it
- use "footers" instead of "fields". more intuitive, i think
- add some "docu" to the footer templates
- refer to the commit policy at the bottom

Change-Id: Ic1ee454a9535bc9e16aa716043605f57ca79f444
Sanity-Review: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>
Reviewed-by: Sergio Ahumada <sergio.ahumada@nokia.com>
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>
Reviewed-by: Rohan McGovern <rohan.mcgovern@nokia.com>

.commit-template

@@ -1,10 +1,18 @@
-# ===[ Subject ]==========[ one line, please wrap at 72 characters ]===|
+# ==[ Subject: One line only short meaningful description for logs ]===|
 
-# ---[ Details ]---------[ remember extra blank line after subject ]---|
 
-# ---[ Fields ]-----------------[ uncomment and edit as applicable ]---|
+# ==[ Details: Describe what changed and explain why it changed ]======|
 
-#Task-number:
-#Reviewed-by:
 
-# ==================================[ please wrap at 72 characters ]===|
+# ==[ Footers: Uncomment and edit where applicable ]===================|
+#
+# One task per entry. Remember space after colon.
+#Task-number: 
+#
+# Solicit reviewers. They still need to use the Gerrit frontend.
+#Reviewed-by: 
+
+# ==[ Please wrap at 72 characters ]===================================|
+#
+# Remember to read http://wiki.qt-project.org/Commit_Policy
+#