Move Configuration documentation from README to Wiki

[55728]

Summary

Moves the Configuration section from the README to the Wiki, as agreed in #289.

What changed

The README's Configuration section (~530 lines covering initializer settings, Scopes, Claims, Routes, Nonces, I18n, and Dynamic Client Registration) is replaced with a concise pointer to the Wiki pages.

Wiki pages (already published)

Page	Content
Configuration	Initializer settings (issuer, subject, signing_key, auth_time, etc.)
Scopes	openid scope setup, offline_access recipe
Claims	Custom claims DSL, acr/amr
Routes	Mounted routes, jwks_uri customization, multi-mount
Nonces	Authorization view nonce pass-through
I18n	Locale file overrides
Dynamic Client Registration	RFC 7591 setup, supported params, authorization

Migration approach

The Wiki content was built in three commits to preserve traceability:

1. Mechanical copy — README Configuration section copied verbatim to Configuration.md
2. Link fix — Repository-relative paths and bare #NNN references converted to absolute URLs
3. Split — Single page split into 7 topic pages with heading promotion

Closes #289