docs: ran spell check and made corrections. Addresses issue #67.

[codecov-commenter]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (d13de59) 80.11% compared to head (767d32c) 80.07%. Report is 1 commits behind head on master.

Files	Patch %	Lines
R/dirs.R	0.00%	2 Missing :warning:

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #100 +/- ## ========================================== - Coverage 80.11% 80.07% -0.05% ========================================== Files 21 21 Lines 3707 3709 +2 ========================================== Hits 2970 2970 - Misses 737 739 +2 ```

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