Docs: Spell check corrections

Docs: Spell check corrections

I walked through all the docs (except for release notes) and made a
number of small corrections. Most of them are simple typos, but there
are a few special cases:

  - In cases where the correction required matching with actual code or
    labels in Evergreen, those were checked to make sure the correction
    matched.
  - Changed spelling of "correct" word "Transcendent" to match database
    spelling "transcendant"
  - Changed very informal contractions "it'll" and "that'll" to "it
    will" and "that will". Same for "whatever's" to "whatever is".
  - Changed very informal expressions: "handwaving" to "glossing",
    "modernish" to "modern", "deduping" to "deduplicating".
  - Changed "unclick" to "uncheck" (regarding a checkbox)

Signed-off-by: Remington Steed <rjs7@calvin.edu>