docs: fixed 'a/an' issues and rephrased some of the text

[septicalls]

Description

Grammatical issues pertaining to the 'a/an' indefinite articles are fixed. Some of the text has been rephrased for better readability.

As this is a minor update to the documentation only, a corresponding issue is not created.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update
• Documentation update

[giarve]

Thanks!