Update README.md
Support rendering ProjectDocumentationWidgets

Project documentation widgets can now be added to pages by adding an element with a data-documentation-widget='project-id' attribute.
The documenation content is looked up from the Spring Framework web server using a JSONP call.
Refactoring ProjectDocumentationWidget
Refactored ProjectModel

[#52044647]
Added .idea to gitignore
Merge commit 'ed58c82fd4e7653aa1bb1be4b58534e85c823f84' into gh-pages

# By Kurtis Seebaldt and Nick Street (2) and others
* commit 'ed58c82fd4e7653aa1bb1be4b58534e85c823f84':
  Refactored ProjectModel
  Refactoring ProjectDocumentationWidget
  Support rendering ProjectDocumentationWidgets
  Update README.md
Projects can now add documentation and quickstart widgets

[#52044647]
Merge commit 'd196a523ca28babdb323a7ddc372cba26aab47fa' into gh-pages

* commit 'd196a523ca28babdb323a7ddc372cba26aab47fa':
  Projects can now add documentation and quickstart widgets
Display quickstart and documentation widgets

[#52044647]