Typo/grammar corrections.

Note: "welcome to django-extensions's documentation" could have been corrected to "welcome to django-extensions' documentation" but I opted for "welcome to the django-extensions documentation" because that feels more natural and is easier to read.
Typo/grammar corrections.
Typo/grammar corrections.
Typo/grammar corrections.
Typo/grammar corrections.

Note: also included a minor sentence restructuring.
Typo/grammar corrections.
Typo/grammar corrections.
Typo/grammar corrections.
Typo/grammar corrections.
Typo/grammar corrections.

Note: included crontab formatting change for improved legibility.
Typo/grammar corrections.
Typo/grammar corrections.
Typo/grammar corrections.

Note: slightly rearranged intro section for improved legibility.
Typo/grammar corrections.

Note: I've edited a number of paragraphs for better legibility - mostly rephrasing and splitting into shorter paragraphs.
Typo/grammar corrections.
Typo/grammar corrections.
Typo/grammar corrections.
Typo/grammar corrections.
Merge pull request #427 from jpoesen/patch-1

Typo/grammar corrections.
Merge pull request #428 from jpoesen/patch-2

Typo/grammar corrections.