Description

Based on the following feedback tickets, I edited some of the pages in the manual:

• DOCATT-8537: Clarified the installation requirements, including adhering to doc standards more (with step-based procedure and adjusted titles).
• DOCATT-8578: Merged duplicated information on Control paths between the API docs and the manual. Whenever there was a discrepancy, I used the guidance from the API docs (for example, the manual said that <layoutName>{usageName}controlName#(displayName) was the composition of the path, while the InputControlPath class said it was <Layout>{Usage}#(DisplayName)Name).
• DOCATT-8743: Edited several MD files connected to the concepts for bindings, input, and controls, including merging some of the manual & API documentation for InputControl & PlayerInput classes and fixing some links to nonexistent anchors.
• DOCATT-9373: Removed the incomplete sentence from the InputActionPhase.Canceled enum value doc.

In addition to those content changes, I also performed a number of changes across several pages that were either structural or more global fixes, which I made in separate commits for clarity:

• Added missing UIDs to manual pages: this was in preparation to convert all links using relative paths to use xref/uid values.
• Normalized "NOTE" and "IMPORTANT" admonitions throughout docs because they were extremely inconsistent in terms of styling and presentation, and most of them didn't use the built-in DocFx support for admonitions.
• Applied standards for images, including more consistent sizing and web accessibility-compliant alt text. Also removed unnecessary screen shots of the Editor where possible (to avoid version-specific inconsistencies).
• Removed mini-TOCS that appeared on some (but not all) manual pages. These weren't compliant with the documentation standards and weren't automated, so some were missing sections that had been added later. And DocFx already generates mini-TOCs for the sidebar, so they were redundant.
• Replaced all links using relative paths with xrefs. These were links to pages in the manual and API docs inside the package as well as links to the Engine docs.

Testing status & QA

• Generated the documentation locally.

Overall Product Risks

Low risk, since no code was modified.

Comments to reviewers

• Some of the changes I made affected most or all manual pages, such as replacing relative links with xref-based links, but I made sure to use a separate commit to make it easier to see the changes that were content-only.
• Any time I made changes to headings I updated any links referring to those headings.

Checklist

• No changelog entry added..
• Commit message for squash-merge is prefixed with DOCS: .
• No forward/backward port needed.