doc: fix typo in BUILDING.md

e.g., to e.g. at BUILDING.md line 116

PR-URL: https://github.com/nodejs/node/pull/9569
Reviewed-By: Roman Reiss <me@silverwind.io>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Shigeki Ohtsu <ohtsu@ohtsu.org>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

BUILDING.md

@@ -123,7 +123,7 @@ To test if Node.js was built correctly:
 > Release\node -e "console.log('Hello from Node.js', process.version)"
 ```
 
-### Android / Android-based devices (e.g., Firefox OS)
+### Android / Android-based devices (e.g. Firefox OS)
 
 Although these instructions for building on Android are provided, please note
 that Android is not an officially supported platform at this time. Patches to