Settings docs accuracy audit: gap fixes and three new pages (#936)

* Enforce periodic user authentication

* Multi-Factor Authentication

* IPv6 minor fixes

* Delete account clarification

* Notifications, perms, and billing

* Update metrics, auto-update, lazy connections

* Settings docs audit fixes plus two new pages

* Update self-hosted notications

* rework client page and navigation

* Matching naming to product

* Coberabbit suggested fixes

* Peer Session Expiration title

* Remove dash

src/pages/get-started/cli.mdx

@@ -694,6 +694,7 @@ sudo netbird service install --config /opt/netbird/config.json
 
 #### Service-specific flags
 ```shell
+      --disable-networks          Disables network selection.
       --disable-profiles          Disables profiles feature.
       --disable-update-settings   Disables update settings feature.
       --service-env strings       Sets extra environment variables for the service. You can specify a comma-separated list of KEY=VALUE pairs. E.g. --service-env NB_LOG_LEVEL=debug,CUSTOM_VAR=value
@@ -701,6 +702,7 @@ sudo netbird service install --config /opt/netbird/config.json
 
 These flags are intended for managed or shared machines where non-admin users should not be able to alter the client configuration through the CLI or UI:
 
+- `--disable-networks` prevents users from listing, selecting, or deselecting networks (including exit nodes) via CLI or UI. The flag is persisted in the service's `service.json` state file; there is no `NB_DISABLE_NETWORKS` environment-variable equivalent.
 - `--disable-profiles` prevents users from adding, removing, or switching profiles. The client stays locked to the profile that was active at install time. Any attempt to switch profiles via CLI or UI is rejected.
 - `--disable-update-settings` prevents users from changing daemon settings (management URL, log level, DNS resolver address, etc.) via CLI or UI. The configuration can only be changed by an administrator who reinstalls the service or uses `service reconfigure`.