fixed missing verb

solves #50

Author: ChristianKuehnel

discourse_migration/userguide.md

@@ -1,7 +1,7 @@
 # [draft] User guide for the (potential) migration of the mailing lists
 
 This document is intended to help LLVM users to migrate from the mailing lists to
-Discourse. Discourse two basic ways for interaction: Via the [web
+Discourse. Discourse has two basic ways for interaction: Via the [web
 UI](https://llvm.discourse.group/) and via emails.
 
 ## Setting up your account