Merge pull request #557 from mcarmonaa/fix/docs-optional-dependencies

docs: fix optional dependencies

Author: ajnavarro

docs/using-gitbase/getting-started.md

@@ -2,7 +2,7 @@
 
 ## Prerequisites
 
-`gitbase` has two optional dependencies that should be running on your system if you're planning on using certain functionality.
+`gitbase` optional dependencies that should be running on your system if you're planning on using certain functionality.
 
 - [bblfsh](https://github.com/bblfsh/bblfshd) >= 2.6.1 (only if you're planning to use the `UAST` functionality provided in gitbase)