Merge pull request #1710 from mattermost/plt-1498

PLT-1498 Add hashtag testing and allow special german characters

doc/developer/tests/test-hashtags.md

@@ -0,0 +1,20 @@
+# Hashtag Testing
+
+Hashtags in Mattermosts should render as specified below. 
+
+#### These strings should auto-link:
+
+#testing
+#testing123
+#test-test
+#test_test
+#test! (punctuation should be excluded from linking)
+#test1 #test2
+#hüllo
+
+#### These strings should not auto-link:
+
+#123test
+#?test
+#-test
+