Firetitle XUL EndOfLife warning

Firetitle_EOL.md

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+FireTitle
+=========
+
+Thanks for installing/upgrading FireTitle.
+
+This is the last upgrade of FireTitle XUL version. It won't be supported
+anymore as it won't work on Firefox 57+ versions.
+
+There is a new Webextension version, called (for now) "Crappy Firetitle". This
+version is still experimental and has less features that the original FireTitle
+add-on since it is constrained by [WebExtensions
+APIs](https://wiki.mozilla.org/WebExtensions).
+
+We hope Firefox developers will enable us to port the missing features before
+Firefox 57 release so that _Crappy Firetitle_ won't be that crappy.
+
+## Links
+
+Mozilla's _Add-ons for Firefox_: 
+
+* [FireTitle project page](https://github.com/captnfab/FireTitle)
+* [Crappy Firetitle](https://addons.mozilla.org/addon/crappy-firetitle/) ([download](https://addons.mozilla.org/downloads/latest/850618/))