metainfo: Release v2.0.15

Adding clarification regarding multiple characters for showchars.

Closes #3938

data/io.github.zyedidia.micro.metainfo.xml

@@ -25,6 +25,7 @@
 		<category>TextEditor</category>
 	</categories>
 	<releases>
+			<release version="2.0.15" date="2025-12-31"/>
 			<release version="2.0.14" date="2024-08-27"/>
 			<release version="2.0.13" date="2023-10-22"/>
 			<release version="2.0.12" date="2023-09-06"/>

runtime/help/options.md

@@ -400,6 +400,10 @@ Here are the available options:
                instead.
    - `itab`: tab characters before the first visible character in a line.
              If this is not set, `tab` will be shown instead.
+
+   Only `tab` and `itab` can display multiple characters (if possible),
+   otherwise only the first character will be displayed.
+
    An example of this option value could be `tab=>,space=.,itab=|>,ispace=|`
 
    The color of the shown character is determined by the `indent-char`