Merge pull request #3709 from metabase/heroku-docs-formatting

Minor docs formatting

docs/operations-guide/running-metabase-on-heroku.md

@@ -45,15 +45,21 @@ Here's each step:
 
 * Clone the latest version to your local machine:
 
-    git clone https://github.com/metabase/metabase-deploy.git  
-    cd metabase-deploy
+```bash
+git clone https://github.com/metabase/metabase-deploy.git  
+cd metabase-deploy
+```
 
 * Add a git remote with your metabase setup:
 
-    git remote add heroku https://git.heroku.com/your-metabase-app.git
+```bash
+git remote add heroku https://git.heroku.com/your-metabase-app.git
+```
 
 * Force push the new version to Heroku:
 
-    git push -f heroku master
+```bash
+git push -f heroku master
+```
 
 * Wait for the deploy to finish