Update basic-writing-and-formatting-syntax.md (github#27074)

Co-authored-by: Vanessa <[email protected]>

Author: slgraff

content/get-started/writing-on-github/getting-started-with-writing-and-formatting-on-github/basic-writing-and-formatting-syntax.md

@@ -317,6 +317,8 @@ The footnote will render like this:
 
 **Note**: The position of a footnote in your Markdown does not influence where the footnote will be rendered. You can write a footnote right after your reference to the footnote, and the footnote will still render at the bottom of the Markdown.
 
+Footnotes are not supported in wikis.
+
 {% endtip %}
 {% endif %}