Refine the install guide

.gitignore

 *.sw*
 .DS_Store
+docs/dl/fonts.tgz
 site/

docs/install.md

 This page, based on the
 [original announcement protocol](https://github.com/biotorrents/announcement),
 is an attempt to make an evergreen install guide.
-It's fast paced and covers only the essentials.
+It's fast paced and only covers the essentials.
 
 # Debian system profile
 
 
 The `/etc/sphinxsearch/sphinx.conf` content is too large to reasonably inline.
 Please find a copy at
-[biotorrents/documentation](https://github.com/biotorrents/documentation/blob/master/sphinx.conf).
+[biotorrents/documentation](https://github.com/biotorrents/documentation/blob/master/docs/dl/sphinx.conf).
 The only other Sphinx-related configs are root crontab entries:
 
 ```crontab
 
 Install SassC with `apt install sassc`.
 
-[Download the font pack](https://docs.biotorrents.de/fonts.tgz)
+[Download the font pack](https://docs.biotorrents.de/dl/fonts.tgz)
 and extract it with:
 `tar zxvf fonts.tgz -C /var/www/html/dev.biotorrents.de/static/styles/assets/fonts`.
 
 | qBittorrent 3.x.y | `-qB3`  |
 | qBittorrent 4.x.y | `-qB4`  |
 | Transmission 2.xy | `-TR2`  |
+| Transmission 3.xy | `-TR3`  |
 
 Most of the Toolbox pages don't write to the database and all of them should work.
 For more BitTorrents info see
 [Calomel's rTorrent hacking guide](https://calomel.org/rtorrent_mods.html).
+
+## Building this documentation
+
+[biotorrents/documentation](https://github.com/biotorrents/documentation)
+has the Mkdocs source code.
+Install MkDocs with `apt install mkdocs`.
+Then do `mkdocs build`.

mkdocs.yml

-site_name: 'Docs ⸬ BioTorrents.de'
-site_url: 'https://docs.biotorrents.de'
+strict: true
 
-repo_name: 'Gazelle'
-repo_url: 'https://github.com/biotorrents/gazelle'
+site_name: "Docs ⸬ BioTorrents.de"
+site_url: "https://docs.biotorrents.de"
+
+repo_url: "https://github.com/biotorrents/gazelle"
+edit_uri: ""
 
 nav:
-  - 'index.md'
-  - 'torrents.md'
-  - 'users.md'
-  - 'forums.md'
-  - 'meta.md'
-  - 'install.md'
+  - "index.md"
+  - "torrents.md"
+  - "users.md"
+  - "forums.md"
+  - "meta.md"
+  - "install.md"
+
+markdown_extensions:
+  - smarty