Updated documentation for asynchronous services
Mark all synchronous extensions as obsolete
Create shared tokens for external links
Wrap text block in para tags for proper formatting
Rewrote the breaking changes policy to clarify many points
Merge pull request #412 from sharwell/obsolete-sync

Mark all synchronous extensions as obsolete
Merge pull request #413 from sharwell/updated-docs

Updated docs
Fix errors in asynchronous example code
Merge pull request #414 from sharwell/must-wait

Fix errors in asynchronous example code