Summary:The "Android Support Library" package is now named "Local Maven repository for Support Libraries", so this updates the docs and screenshot accordingly.

Closes https://github.com/facebook/react-native/pull/6185

Reviewed By: mkonicek

Differential Revision:D3017638
Ninja: oss only (rn website)

Pulled By: mkonicek

fb-gh-sync-id: 3559a9f09930e7606af7912e7aaee3c4215c1b03
shipit-source-id: 3559a9f09930e7606af7912e7aaee3c4215c1b03