Merge branch 'update_doc' into 'master'

Update to 4.3 doc needs unicorn config copy

doc/update/4.2-to-4.3.md

@@ -22,6 +22,15 @@ git checkout 4-3-stable
 ### 4. Install libs, migrations etc
+Edit web server settings
+
+```
+cp config/unicorn.rb.example config/unicorn.rb
+editor config/unicorn.rb
+```
+
+Then:
+
 ```
 # For MySQL users
 bundle install --without postgres development test --deployment