Merge branch 'improve-get-started' into 'master'

Add FreeBSD to prepare.md

Add FreeBSD install instructions to prepare.md and improve pre-requisites section.

See merge request !196

doc/prepare.md

@@ -129,6 +129,15 @@ binary version of Git.
 You may need to install Redis 2.8 or newer manually.
+### FreeBSD
+
+Please read [the prerequisites for all platforms](#prerequisites-for-all-platforms).
+
+```
+sudo pkg install postgresql93-server postgresql93-contrib postgresql-libpqxx \
+redis go node icu krb5 phantomjs gmake
+```
+
 ### Other platforms
 If you got GDK running an another platform please send a merge request to add