[docs] Fix various typos and grammatical errors

[kevburnsjr]

Fix various typos and grammatical errors

[codecov-commenter]

Codecov Report

Patch coverage has no change and project coverage change: +0.22 :tada:

Comparison is base (023bafb) 84.53% compared to head (4a38b93) 84.74%.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #297 +/- ## ========================================== + Coverage 84.53% 84.74% +0.22% ========================================== Files 10 10 Lines 4264 4264 ========================================== + Hits 3604 3613 +9 + Misses 404 400 -4 + Partials 256 251 -5 ``` | [Impacted Files](https://codecov.io/gh/lni/dragonboat/pull/297?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=lni) | Coverage Δ | | |---|---|---| | [nodehost.go](https://codecov.io/gh/lni/dragonboat/pull/297?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=lni#diff-bm9kZWhvc3QuZ28=) | `87.08% <ø> (+0.20%)` | :arrow_up: | ... and [4 files with indirect coverage changes](https://codecov.io/gh/lni/dragonboat/pull/297/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=lni) Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=lni). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=lni)

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[kevburnsjr]