Update WebC doc

[d3v1an7]

Hi there, this is a bit of a chonky boi!

I recently had to write some autocomplete notes for a WebC VS Code extension, and figured I should have a shot at applying what I learned in that process to the official docs.

There are a few unrelated changes (direct phrasing, minor typos, adding/fixing links), but the main point of the PR is a revamp of what was previously bundled as the WebC Reference.

Key changes

1. WebC Reference has been removed, in favour of the following groups:
   • Components and output
   • Attributes, props and slots
   • Rendering content
   • Scripts and styles
   • Opting out of WebC processing
   • Subtleties and limitations
2. All code examples have had some love. They are opinionated updates, based on my own struggles, experimentations and discoveries over the years. I've tried to keep to a consistent(ish) theme (POSSUMS), to help the examples feel more cohesive.
3. I've tried to stick with a consistent writing style when introducing each item: Verb led (Keeps, Imports, Replaces), and I try to state what the attribute does to its element within one sentence, followed by caveats and code example/s.

Anchor changes

There are handful of anchor additions/removals, along with some changes to existing anchors:

Old	New
webcfor-loops	webcfor
using-java-script-to-setup-your-component	webcsetup
java-script-render-functions-webctypejs-and-webctyperender	webctypejs
using-template-syntax-to-generate-content	webctype11ty-and-11tytype
using-java-script-to-generate-content	webctype
components, components-2	head-components, table-components
webcscopedmy-prefix, arrays-(or-any-other-iterable), objects, nesting, nesting-webcfor	removed

AI disclaimer

Claude was used to sense check, compare against my WIP styleguide, and run each code example to ensure the output examples are correct. Some of the attribute descriptions had a first pass from Claude (help getting the correct verb or sentence shorter), but all copy has been human edited.