Add Welcome section to docs

* Fixes unrelated typo in readme
* Add new Welcome section with history, team, callouts, and community
subsections
* Redesigns callouts to be a bit lighterweight with colored headings
shorter avatar urls
use irc link
Merge branch 'master' into docs_welcome
Copy edits from @cvrebert and @juthilo
dat @juthilo edit
dat hash
move to separate about page
fix #11003
use CDN for respond.js
add translations, copy edit a few things, and fix alignment of ads
Merge branch 'docs_welcome'
avoid referencing /docs-assets/ in Getting Started docs example; use CDN URL for respond.js
Merge pull request #11075 from twbs/respond-js-cross-domain-note

fix #11003
Merge pull request #11077 from twbs/avoid-docs-assets-in-example

avoid referencing /docs-assets/ in Getting Started docs example; use CDN URL for respond.js
Merge pull request #11076 from twbs/respond-js-cdn

use CDN for respond.js
update to latest jszip
commit 04fc93045334dc1b679aba5c2dce206da777a85c
2013-10-12T12:39:56-07:00