r: add matrixirc2 / matrixforirc(user)

I could have linked there dozens of times if I had written it
previously, but better late than never. I also should possibly have used
a better URL for the bridged IRC networks, but done is done.

r/matrixirc2.md

@@ -0,0 +1,8 @@
+---
+redirect_to: https://github.com/matrix-org/matrix-appservice-irc/wiki/Matrix-for-IRC-user
+permalink: /r/matrixirc2.html
+redirect_from:
+  - /r/matrixforirc.html
+  - /r/matrixforircuser.html
+sitemap: false
+---