Fix grammar and markdown format

[jerone]

Fix a few grammar mistakes.

Linted Markdown:

• Trailing spaces.
• Multiple consecutive blank lines.
• Headings without surrounded blank lines.
• Fenced code blocks without surrounded blank lines.
• Missing alt text.
• Dead link references.

[codecov[bot]]

Codecov Report

Patch and project coverage have no change.

Comparison is base (40431f4) 20.66% compared to head (6490c5c) 20.66%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #533 +/- ## ======================================= Coverage 20.66% 20.66% ======================================= Files 8 8 Lines 479 479 Branches 103 103 ======================================= Hits 99 99 Misses 377 377 Partials 3 3 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Do you have feedback about the report comment? Let us know in this issue.

[jerone]

Closing as project seems unmaintained.