Merge pull request #252 from matrix9180/patch-1

Update Development-guide.md

Running-Mastodon/Development-guide.md

@@ -62,7 +62,7 @@ These are self-contained instructions for setting up a development environment o
 - Get [Homebrew](https://brew.sh) and use it to install the other dependencies:
 
 	```
-	brew install imagemagick ffmpeg yarn postgresql redis rbenv nodejs
+	brew install imagemagick ffmpeg yarn postgresql redis rbenv nodejs protobuf
 	```
 
 - Configure Rbenv: