Edits README for clarity and formatting
Adds to introduction and replaces first section
Expands Ruby Gem, Before Changes, & Making Changes sections
Finalizes first draft
Makes minor edits for clarity and voice
Updates README to follow contribute.textile more closely
Edits README for clarity and consistency
Fixes some typos
Fixes indexing of Contribute guide

The guides gem indexer was choking because the sample guide in the
"Creating or Modifying a Guide" section had a line that started
with "h3. ". This commit fixes that by adding two spaces to each
line in that sample guide snippet.
Merge pull request #123 from toasterlovin/contribute

Update and expand Contribute Guide and README