docs(usage-and-behavior): updates usage and behavior guidelines as pa…

…rt of content audit. (#3735)

* docs(usage-and-behavior): updates usage and behavior guidelines as part of content audit.

* Updates br line break tags.

* Adjust page and title naming.

* Spell check

* Update packages/documentation-site/patternfly-docs/content/design-guidelines/usage-and-behavior/usage-and-behavior.md

* Update usage-and-behavior.md

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Co-authored-by: Margot <[email protected]>