colon after YML variables

Author: seaxwi

_linter/markdownlint/Rules.md

@@ -62,15 +62,15 @@ Note that the error can also be triggered by a mispelling, such as
 
 ```
 ---
-tile "Article title"
+tile: "Article title"
 ---
 ```
 
 instead of
 
 ```
 ---
-title "Article title"
+title: "Article title"
 ---
 ```
 
@@ -90,15 +90,15 @@ Note that the error can also be triggered by a mispelling, such as
 
 ```
 ---
-tile "Article title"
+tile: "Article title"
 ---
 ```
 
 instead of
 
 ```
 ---
-title "Article title"
+title: "Article title"
 ---
 ```