* Added description of the current HDF5 branches.
* Removed capitalization in from Develop, Release, Feature to reflect the real naming schema
* Added a draft of contributions guidance document.
* Fixed typos.
* Fixed section title.
* Fixed typo.
* Fixed typos and formatting.
* Fixed many typos and simplified the text (e.g., removed testing instructions and left pointers to where to find them, etc.)
* Fixed a typo.
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* Added contributing.md file and rearranged doc entries in alphabetical order.
* ddressed Gerd's review comments; found and fixed more typos.
* Addressed comments from Larry and Scot.
