Improvements to Q# library documentation

[filipw]

• fixed typos and inconsistencies in documentation
• in some cases the same typos were copied/propagated to many places:
  • auxilliary instead of auxiliary
  • anthing instead of anything
  • lease instead of least
  • Identitfy instead of Identify
• in some cases the symbol names in the docs did not match the actual symbols in the code

There are no logical code changes here, it's only docs, so it should be sage to merge.

[minestarks]

Thank you for taking the time to fix these!