[23] Improve BLANK variable docs

Author: CollinHeist

backend/.version

@@ -1 +1 @@
-v2.16.0-webui22
+v2.16.0-webui23

docs/user_guide/variables.md

@@ -137,7 +137,7 @@ hypothetical TCM customizations.
     | `extras`      | Any assigned extras                    | _See below_ |
     | `NEWLINE`     | A character to move text to a new line | `\n`        |
     | `BACKSLASH`   | The ++backslash++ character            | `\`         |
-    | `BLANK`       | Blank text[^6]                         | ``          |
+    | `BLANK`       | Blank text[^6]                         |             |
 
     Any assigned extras are added as their variable name. For example, if I
     specify the "Episode Text Color" extra for the Series, then the variable