Update README.md to revise Heroku paid plan

Heroku instance is only available on paid plan.

README.md

@@ -106,9 +106,7 @@ Please see [the Huginn Wiki](https://github.com/huginn/huginn/wiki#deploying-hug
 
 ### Heroku
 
-Try Huginn on Heroku: [![Deploy](https://www.herokucdn.com/deploy/button.png)](https://heroku.com/deploy) (Takes a few minutes to setup. Read the [documentation](https://github.com/huginn/huginn/blob/master/doc/heroku/install.md) while you are waiting and be sure to click 'View it' after launch!)
-
-Huginn launches on the free version of Heroku [with significant limitations](https://github.com/huginn/huginn/blob/master/doc/heroku/install.md). For non-experimental use, we strongly recommend Heroku's 1GB paid plan or our Docker container.
+Try Huginn on Heroku: [![Deploy](https://www.herokucdn.com/deploy/button.png)](https://heroku.com/deploy) (Takes a few minutes to setup. Read the [documentation](https://github.com/huginn/huginn/blob/master/doc/heroku/install.md) while you are waiting and be sure to click 'View it' after launch!) Huginn launches only on a paid subscription plan for Heroku. For non-experimental use, we strongly recommend Heroku's 1GB paid plan or our Docker container.
 
 ### OpenShift