README: link to bridgy m.facebook.com scraping issue

README.md

@@ -310,7 +310,7 @@ Changelog
 ---
 ### 2.2 - unreleased
 * Facebook:
-  * Add `get_activities(scrape=True)` for scraping HTML from [m.facebook.com](https://m.facebook.com/). Requires `c_user` and `xs` cookies from a logged in session.
+  * Add `get_activities(scrape=True)` for scraping HTML from [m.facebook.com](https://m.facebook.com/). Requires `c_user` and `xs` cookies from a logged in session. ([snarfed/bridgy#886](https://github.com/snarfed/bridgy/issues/886)
 
 ### 2.1 - 2019-09-04
 * Convert AS2 `Mention` tags to AS1 `objectType` `mention` (non-standard) and vice versa ([snarfed/bridgy-fed#46](https://github.com/snarfed/bridgy-fed/issues/46)).