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/text-mode/email

@@ -1,4 +1,4 @@
-#name : (user's email)
+# name: (user's email)
 # key: email
 # --
 `(replace-regexp-in-string "@" "@NOSPAM." user-mail-address)`

snippets/text-mode/time

@@ -1,4 +1,4 @@
-#name : (current time)
+# name: (current time)
 # key: time
 # --
 `(current-time-string)`