MINOR: Improve introduction section in docs to better cover connect and streams. Make uses and ecosystem pages stand alone.

Often it is useful to link to a specific header within the documentation. Especially when referencing docs in the mailing lists.

This adds anchors and links for all headers in the docs.

Author: Grant Henke <granthenke@gmail.com>

Reviewers: Jun Rao <junrao@gmail.com>

Closes #498 from granthenke/doc-links

This PR copies the latest kafka docs to kafka repo docs directory. Here I have copied 0.8.3/ directory contents from svn website repo to kafka/docs repository.

Some questions: This PR contains generated javadocs also.  Do we need to copy javadocs here?

Author: Manikumar reddy O <manikumar.reddy@gmail.com>

Reviewers: Gwen Shapira, Ismael Juma

Closes #171 from omkreddy/KAFKA-2425-MOVE-DOCS-TO-KAFKA-REPO