docs: fix broken anchors and stale Doctrine annotation references

[oojacoboo]

Summary

Doctrine annotation support was dropped in #677, and the relevant section headings were subsequently renamed from "annotation(s)" to "attribute(s)". A handful of in-repo links and wording were missed in that rename — this PR cleans them up.

Broken anchors (navigation currently breaks)

• annotations-reference.md #[Type] section: #input-annotation / #factory-annotation → #input / #factory (sections are now ## #[Input] and ## #[Factory]).
• authentication-authorization.mdx + fine-grained-security.mdx: #logged-and-right-annotations → #logged-and-right-attributes (section is ## #[Logged]and#[Right] attributes).

Stale / contradictory wording

• queries.mdx "About attributes": the Doctrine example was shown as #[Query], which is the new-style syntax. Corrected to @Query and rephrased so the old-vs-new distinction actually reads.
• annotations-reference.md intro: reworded to reflect that only the PHP 8 attribute format exists now. Kept the link to the migration guide since existing users still benefit from it.
• annotations-reference.md #[Assertion]: Type column said annotation while the description said attributes — aligned to attribute.

Intentionally left alone

• CHANGELOG.md — historical record.
• migrating.md — historical migration guide, references @SourceField etc. on purpose.
• doctrine-annotations-attributes.mdx — migration guide, still useful for users on the old syntax.
• annotations parameter on #[SourceField] / #[MagicField] — that's the actual PHP parameter name in the source, not stale terminology.
• PHP namespace references like TheCodingMachine\GraphQLite\Annotations\* — real symbol names.

Test plan

• Diff is link/wording changes only; no structural or behavioral edits.
• Render the Docusaurus site locally and click through the four affected pages to confirm the anchor links land on the right sections.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.84%. Comparing base (53f9d49) to head (6340e58).
⚠️ Report is 150 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #799      +/-   ##
============================================
- Coverage     95.72%   94.84%   -0.89%     
- Complexity     1773     1869      +96     
============================================
  Files           154      175      +21     
  Lines          4586     5079     +493     
============================================
+ Hits           4390     4817     +427     
- Misses          196      262      +66     

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