Consolidate legacy root-level implementation markdown docs into /docs

[Chigybillionz]

Consolidate legacy root-level implementation markdown docs into /docs

Close #456

Summary of the issue
The repo root contained multiple legacy “implementation-notes” markdown files alongside the existing docs/ directory, cluttering the root and making it hard for contributors to distinguish current documentation from historical PR notes.

Root cause
Legacy docs were added/kept at the repo root instead of being consolidated under the existing docs/ structure, resulting in duplicated and confusing documentation location conventions.

Solution implemented
Moved all legacy root-level implementation markdown docs into a structured /docs hierarchy:

docs/page-transitions/
docs/pull-to-refresh/
docs/project/
Removed the empty stray add.md. Updated README.md with an “Additional documentation” section linking to these consolidated doc areas.

Key changes made
Relocated page-transition documentation files into docs/page-transitions/
Relocated pull-to-refresh documentation files into docs/pull-to-refresh/
Relocated project-level implementation summary/docs into docs/project/
Kept FORCED_COLORS_GUIDELINES.md as a legacy copy under docs/project/ to avoid silently losing any content vs the existing docs/forced-colors-guide.md
Deleted the empty add.md
Updated README.md to include section-level links to the new docs structure
Any trade-offs or considerations
FORCED_COLORS_GUIDELINES.md vs docs/forced-colors-guide.md:
To satisfy “no content silently lost”, the legacy root version was preserved under docs/project/ rather than deleting/overwriting the existing doc.
Testing steps (how to verify the fix)
Confirm each moved doc exists at its new path under /docs/...
Confirm add.md is removed
Open README.md and verify “Additional documentation” links render correctly
Run tests/lint (pending environment dependency install):
npm test
npm run lint

Please kindly review this task. If there are any corrections, improvements, adjustments, or merge conflicts that you notice regarding my implementation, I'd really appreciate your feedback. I'd also love to hear your overall review of my work on this branch. Thank you!