docs (generators): Heroku generator run manually

Remove 'yo angular-fullstack:heroku' (not working)
Update docs to reflect manual setup

Fixes: angular-fullstack#1966, angular-fullstack#1950

Author: aniknafs

Diff for: docs/generators/heroku.md

@@ -15,6 +15,7 @@ If you're using mongoDB you will need to add a database to your app:
 heroku addons:create mongolab
 ```
 
+
 Note: if you get an `Error: No valid replicaset instance servers found`  you need to modify moongose connection options in config/environment/production.js as follows:  
 ```
 options: {
@@ -56,7 +57,6 @@ gulp build
 ```
 
 Commit and push the resulting build, located in your dist folder:
-
 ```
 gulp buildcontrol:heroku
 ```