I spent some time slicing-and-dicing the documentation with different 
tools and pipelines to find spelling issues. I ignored changelogs, since 
I don't know if spelling fixes in there would be worthwhile or appreciated.

The attached patch was made against 
7f3877e83405a089b580fe9d0342dc0b6c08cbfc (2018-09-20) and consists 
solely of spelling fixes to documentation. If you would prefer these 
fixes be submitted in a different manner, please let me know.

-Mak