Bug 1629708 - Point to the Eclipse CDT docs from the in-tree docs. r=sylvestre

Maybe we should move that in-tree, at some point.

Depends on D71052

Differential Revision: https://phabricator.services.mozilla.com/D71053

--HG--
extra : moz-landing-system : lando

docs/contributing/editor.rst

@@ -226,6 +226,8 @@ You can generate an Eclipse project by running:
 
     ./mach ide eclipse
 
+See also the `Eclipse CDT <https://developer.mozilla.org/en-US/docs/Mozilla/Developer_guide/Eclipse/Eclipse_CDT>`__ docs on MDN.
+
 Visual Studio
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