fixing og:image url for social site sharing
Merge pull request #867 from agektmr/discovery_and_distribution

fixing og:image url for social site sharing
Merge pull request #866 from CoderK/master

Translated "/fundamentals/performance/index.markdown" and "/fundamentals/performane/critical-rendering-path/index.markdown" into Korean.
Fix issue #870
Merge pull request #871 from jacquerie/issue-870

Fix issue #870
Fixing up some typos and issues with the new tooling docs
fix for #861 #863 #862
article "Optimizing URL Structure for Multi-Device Sites"
hiding articles not complete
Merge pull request #873 from agektmr/social_sharing

Fix for #861 #863 #862
Merge branch 'master' of github.com:google/WebFundamentals

* 'master' of github.com:google/WebFundamentals:
  fix for #861 #863 #862
  Fix issue #870
  fixing og:image url for social site sharing
  revert .gitignore to previous version git
  rename performance/performance/critical-rendering-path -> performance/critical-rendering-path
  fix typo in config files and delete trash file
  translated performane/critical-rendering-path/index.markdown
  Update the schema link for the Github sample
  Translation: /fundamentals/performance/index.markdown
Fixes #875 - added videos to images article
Merge branch 'master' of https://github.com/google/WebFundamentals
Part of #875 - forgot to update updated_on
Fixing up titles to make things a little clearer
Merge branch 'master' of github.com:google/WebFundamentals

* 'master' of github.com:google/WebFundamentals:
  Part of #875 - forgot to update updated_on
  Fixes #875 - added videos to images article
Fixes #777
Meghans fixes and comments
Merge branch 'master' of github.com:google/WebFundamentals

* 'master' of github.com:google/WebFundamentals:
  Fixes #777
Minor tweaks to setup section