Move components wiki information into the git repository.

Currently, we have markdown documentation at the component wiki (https://github.com/Talend/components/wiki). This is really useful to the developer, but is frequently out of date – especially where the version number is hard-coded.

Many other projects include developer docs directly in the git repository with links from the main README.md to the sub-pages. This has two advantages:

1) The documentation can be customized to the branch or version of the repository being used, and

2) You can submit pull requests on documentation and reviews.

There is no disadvantage to including the documentation in the main git repo, except that changes exclusively to documentation should probably never trigger a new build.