Fix formatting errors in user guide

[ang-zeyu]

What is the purpose of this pull request?

• Documentation update
• Bug fix
• Feature addition or enhancement
• Code maintenance
• Others, please explain:

Some of the tags / newlines in the user guide don't observe markdown rules following the implicit fixes in #1403 , and elsewhere

Causing things like this:

Overview of changes:

• change some inline tags to 'block' markdown tags and vice versa
  • changes to inline tags are due to the parent tag not being able to hold 'block' tags
  • changes to block tags (just one) as the parent tag should be able to hold other 'block' tags
• remove some newlines

so everything renders properly

Anything you'd like to highlight / discuss:

Testing instructions:

Proposed commit message: (wrap lines at 72 characters)
Fix formatting errors in user guide

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Checklist: ☑️

• Updated the documentation for feature additions and enhancements
• Added tests for bug fixes or features
• Linked all related issues
• No blatantly unrelated changes
• Pinged someone for a review!

[ang-zeyu]

@ryoarmanda fyi, fixing these collated issues as it would affect reviews in #1478, do rebase / merge on top once done!