Added FSF internship

Author: tachyons

README.md

@@ -15,3 +15,4 @@
 | [OpenDaylight summer internship program] (https://www.opendaylight.org/opendaylight-summer-internship-program) | Yes |
 | [The X.Org Endless Vacation of Code (EVoC)](http://www.x.org/wiki/XorgEVoC/)| Yes |
 | [DataONE Summer Internship Program](https://www.dataone.org/internships) | Yes (USA citizens only)|
+| [Free Software Foundation Internship](http://www.fsf.org/volunteer/internships) | No|