ci(docs): update README.md (#209)

need to include `make install` due to new deps

Author: juancarlostong

README.md

@@ -19,6 +19,7 @@ Installers and binary archives for most platforms can be downloaded directly fro
 ## Running from source (Linux / OSX)
 Once Go is installed, the Optimizely Agent can be started via the following `make` command:
 ```bash
+make install
 make run
 ```
 This will start the Optimizely Agent with the default configuration in the foreground.