docs: document PATCH /graph/v1.0/me no longer accepts password/accountEnabled/onPremisesSamAccountName (#12493)

Automated documentation follow-up for a merged, user-visible API contract change.

### Source
PR #12493 — *fix: [OCISDEV-977] patch me* (merged to `master` 2026-07-07), changelog fragment `changelog/unreleased/enhancement-graph-patch-me-password-change.md` (type: Security).

### What changed (API contract)
`PATCH /graph/v1.0/me` now returns **400 Bad Request** when the request body contains any of:
- `passwordProfile` — password changes must go through `POST /graph/v1.0/me/changePassword`
- `accountEnabled`
- `onPremisesSamAccountName`

Previously these fields were accepted on the self-service `PATCH /me` endpoint. This is a behavior change for any API consumer (SDKs, scripts, web/clients) that changed its own password, enabled/disabled state, or SAM account name via `PATCH /me`.

### Documentation to update
- [ ] **API / Graph endpoint reference** — note the rejected fields on `PATCH /graph/v1.0/me` and point password changes to `POST /me/changePassword`.
- [ ] **Migration / breaking-change note** — call out that clients using `PATCH /me` for password change now receive `400` and must switch to `changePassword`.
- [ ] Confirm the changelog fragment wording matches the docs; verify no admin-facing config/flag docs are affected (none in this PR — code + test + changelog only).

### Notes
- The changelog entry exists; this issue tracks the end-user/API-reference documentation, which is not covered by the changelog fragment alone.
- No admin docs, config options, or deployment-topology requirements were touched by the PR.

_Opened automatically by the oCIS triage routine (PR-merged trigger). Documentation PRs are not auto-merged._

🤖 Generated by Claude Code

Start with changelog/unreleased/enhancement-graph-patch-me-password-change.md and PR #12493, then locate the API reference and migration or breaking-change documentation for PATCH /graph/v1.0/me. Document the rejected fields, direct password changes to POST /graph/v1.0/me/changePassword, and explain the resulting 400 response; confirm the changelog wording is consistent and no admin documentation needs changes.

Written by the indexing model from the issue text.