Update README.md

README.md

@@ -1,8 +1,10 @@
 # PDF.js
 
-This is a fork of PDF.js which works with SeaMonkey 2.49.x and Firefox 52 ESR.
-It probably won't work with later versions of SeaMonkey or Firefox, and I don't
-currently plan on supporting them in this fork.
+This is a fork of PDF.js which works with SeaMonkey 2.49.x and Firefox 52 ESR. It may also work in Pale Moon.
+
+Known issues:
+
+* In SeaMonkey 2.53+, the PDF may fail to load until you press the Stop button in the browser.
 
 For more information about pdf.js, see: https://github.com/mozilla/pdf.js
 
@@ -32,4 +34,5 @@ To build the SeaMonkey extension, run:
 ## Installing
 
 You can get the latest release of this fork from the
-[releases page on GitHub](https://github.com/IsaacSchemm/pdf.js-seamonkey/releases).
+[releases page on GitHub](https://github.com/IsaacSchemm/pdf.js-seamonkey/releases)
+or from [addons.thunderbird.net](https://addons.thunderbird.net/en-US/seamonkey/addon/pdf-js-for-seamonkey/).