Keep snippet vars definitions in a single format across all snippets and documentation.

The format is:

# var-name: value

Previously snippets used a mixture of the following formatting:

#var-name: value
#var-name : value
# var-name: value
# var-name : value

snippets/f90-mode/pr

@@ -1,5 +1,5 @@
-#contributor: Li Zhu <http://www.zhuli.name>
-#name : program ... end program ...
+# contributor: Li Zhu <http://www.zhuli.name>
+# name: program ... end program ...
 # key: pr
 # --
 program ${1:name}