Update README.md

Dead links for installation.
(cherry picked from commit ac67f276ceaa517801b6abc9f0edc30d7e8ce604)

Closes #13857

README.md

@@ -36,10 +36,8 @@ website at [TrinityCore.org](http://www.trinitycore.org).
 
 ## Install
 
-Detailed installation guides are available in the wiki for
-[Windows](http://collab.kpsn.org/display/tc/Win),
-[Linux](http://collab.kpsn.org/display/tc/Linux) and
-[Mac OSX](http://collab.kpsn.org/display/tc/Mac).
+Detailed installation guides are available in the [wiki](http://collab.kpsn.org/display/tc/Installation+Guide) for
+Windows, Linux and Mac OSX.
 
 
 ## Reporting issues