Self-hosting guides corrected for Kura routing and peer TLS

The self-hosting guides were updated to match how the server actually routes the CLI and how multi-node peer TLS works. They no longer tell operators to set TUIST_KURA_ENDPOINTS or server.kuraEndpointUrls, which had no consumer; CLI routing on a self-hosted server is driven by the global TUIST_CACHE_ENDPOINTS (Helm server.cacheEndpointUrl), and node registration is dashboard-only on a self-hosted server. The guides also clarify that KURA_INTERNAL_TLS_* (peer mTLS) is only required for multi-node setups: a single Kura node uses an http:// KURA_NODE_URL with peer TLS off, leaving the host and KURA_INTERNAL_PORT unchanged. The Cache page is documented as available by default on a self-hosted server, so the old “enable the kura flag via /ops/flags” workaround is gone.