turn the extensions gallery into HTML
removed empty section tags that were not even nested correctly. didnt seem to be used for anything
Merge github.com:GoogleChrome/devtools-docs into shortcut-updates

* github.com:GoogleChrome/devtools-docs: (31 commits)
  turn the extensions gallery into HTML
  readme images updated
  Updated image links for docs/elements.html so they don't 404.
  Updated readme links to go to developer.chrome.com
  Removed empty paragraph element. Originally had the table caption for mobile network emualtion but was forgotten.
  Added table for mobile network emulation parameters.
  typo. 2.1 -> 2.
  fixes #6 - typos and corrections
  emulation not behind a setting anymore.
  Update readme.md
  Renamed a mixed-up image. Created new image for small-rows to fit the written content.
  Added some missing images to the network page and re-did their counterparts to keep consistency.
  Update readme.md
  alternate wording on long-resume
  issue #40 - added the long resume to the doc.
  changed ctrl+` back to focus the console since it does both
  added alt+w to close active tab
  flamechart text update
  modified the shortcut ctrl+` to be in all panels, changed to say Open console
  image updates.
  ...
Removed duplicate protocols in webstore links
Updated heading for remote debug protocol v 1.1
Updated out-of-date anchor link.
Minor HTML markup edits.

UI elements should be in <b> not <code>
Wrapped YouTube videos in a .video-container so they can be responsive.

Dependent on CL 291663002 (https://codereview.chromium.org/291663002/#ps100001) going through.
Got rid of max-width so <img> can be responsive.
Merge pull request #99 from pearlchen/master

Minor updates to Remote Debugging and Mobile Emulation pages
Merge pull request #97 from Garbee/protocol

Updated heading for remote debug protocol v 1.1
Merge pull request #96 from Garbee/extension

Removed duplicate protocols in webstore links
Merge pull request #94 from jaredwilli/shortcut-updates

Shortcut updates