Add docs on geolocation

Goes with getsentry/self-hosted#766.

src/components/sidebar.tsx

@@ -102,11 +102,12 @@ export default () => {
         </div>
         <ul className="list-unstyled" data-sidebar-tree>
           <SidebarLink to="/self-hosted/">Overview</SidebarLink>
+          <SidebarLink to="/self-hosted/email/">Email</SidebarLink>
+          <SidebarLink to="/self-hosted/geolocation/">Geolocation</SidebarLink>
           <SidebarLink to="/self-hosted/sso/">Single Sign-On (SSO)</SidebarLink>
           <SidebarLink to="/self-hosted/releases/">
             Versioning & Releases
           </SidebarLink>
-          <SidebarLink to="/self-hosted/email/">Email</SidebarLink>
           <SidebarLink to="/self-hosted/support/">Support</SidebarLink>
         </ul>
       </li>

src/docs/self-hosted/geolocation.mdx

@@ -0,0 +1,26 @@
+---
+title: 'Self-Hosted Geolocation'
+---
+
+Sentry can use [MaxMind's free GeoLite2 database](https://dev.maxmind.com/geoip/geoip2/geolite2/) to geolocate IP addresses, providing additional context for error events where the end-user's IP address is known, as well as for the session history of users logging into your Sentry installation. Our on-premise offering bundles MaxMind's [`geoipupdate`](https://hub.docker.com/r/maxmindinc/geoipupdate) tool for initially downloading and periodically updating this dataset. To enable this functionality, you should sign up for [a free MaxMind account](https://www.maxmind.com/en/geolite2/signup), and then tell Sentry about your credentials via a [`docker-compose.override.yml`](https://docs.docker.com/compose/extends/#understanding-multiple-compose-files) file, like so:
+
+```yaml
+version: '3.4'
+services:
+  geoipupdate:
+    environment:
+      GEOIPUPDATE_ACCOUNT_ID: 012345
+      GEOIPUPDATE_LICENSE_KEY: foobar
+```
+
+By default, `onpremise` is configured to refresh the GeoLite2 database when the `geoipupdate` service first starts, and weekly thereafter. You can change the update frequency with an additional override:
+
+```yaml
+version: '3.4'
+services:
+  geoipupdate:
+    environment:
+      GEOIPUPDATE_ACCOUNT_ID: 012345
+      GEOIPUPDATE_LICENSE_KEY: foobar
+      GEOIPUPDATE_FREQUENCY: 24 # hours
+```

src/docs/self-hosted/index.mdx

@@ -10,9 +10,23 @@ Our recommendation is to download the [latest release of the onpremise reposito
 
 ## Configuration
 
-You are very likely to want to change the default configuration for Sentry. Most, if not all, configuration options that you'd like to tweak are in `sentry/config.yml`, which is generated from [`sentry/config.example.yml`](https://github.com/getsentry/onpremise/blob/master/sentry/config.example.yml) at the time of installation. The file itself documents the most common configuration options as code comments, and you can find more about configuring Sentry over at <Link to="/config/">the configuration section of our developer documentation</Link>. You would likely need to change `system.url-prefix` (this is also prompted at the welcome screen, right after the installation) and settings starting with `mail.` even if we ship with a built-in SMTP server for basic stuff. GitHub and Slack integration settings also reside in this file. For more advanced things, you can have a look at [`sentry/sentry.conf.example.py`](https://github.com/getsentry/onpremise/blob/master/sentry/sentry.conf.example.py).
+You are very likely to want to change the default configuration for Sentry. Here are the three main facilities available to you:
 
-**Once you change your configuration, you'll need to restart all Sentry services by running `docker-compose restart web worker cron sentry-cleanup` (or just `docker-compose restart` to restart everything).**
+1. Most, if not all, configuration options that you'd like to tweak are in `sentry/config.yml`, which is generated from [`sentry/config.example.yml`](https://github.com/getsentry/onpremise/blob/master/sentry/config.example.yml) at the time of installation. The file itself documents the most common configuration options as code comments, and you can find more about configuring Sentry over at <Link to="/config/">the configuration section of our developer documentation</Link>. You would likely need to change `system.url-prefix` (this is also prompted at the welcome screen, right after the installation) and settings starting with `mail.` (though we do ship with a basic SMTP server).  GitHub and Slack integration settings also reside in this file.
+
+1. For more advanced things, you can have a look at [`sentry/sentry.conf.example.py`](https://github.com/getsentry/onpremise/blob/master/sentry/sentry.conf.example.py).
+
+1. You can also use [`docker-compose.override.yml`](https://docs.docker.com/compose/extends/#understanding-multiple-compose-files) to override [our `docker-compose.yml`](https://github.com/getsentry/onpremise/blob/master/docker-compose.yml). This is especially helpful for the few places where we depend on environment variables, such as <Link to="/self-hosted/geolocation/">geolocation</Link>.
+
+<Alert title="Note" level="info">
+  Once you change your configuration, you'll need to restart all Sentry services by running <code>docker-compose restart web worker cron sentry-cleanup</code> (or just <code>docker-compose restart</code> to restart everything).
+</Alert>
+
+Here is further information on specific configuration topics:
+
+- <Link to="/self-hosted/email/">Email</Link>
+- <Link to="/self-hosted/geolocation/">Geolocation</Link>
+- <Link to="/self-hosted/sso/">Single Sign-On (SSO)</Link>
 
 ## Troubleshooting
 

src/docs/self-hosted/sso.mdx

@@ -1,5 +1,5 @@
 ---
-title: 'Single Sign-On (SSO)'
+title: 'Self-Hosted Single Sign-On (SSO)'
 ---
 
 SSO in Sentry is handled in one of two ways: