Make flags additive and clean up docs

This means that you have to turn on features now instead of disabling
them like auth and https.

In addition:
- Allow multiple options for auth (only password for now).
- Combine the install docs since they had many commonalities and
- generally simplified them (hopefully not too much).
- Move all example configs into docs/examples.

doc/quickstart.md

@@ -0,0 +1,57 @@
+# Quickstart Guide
+1. Visit the [releases page](https://github.com/cdr/code-server/releases) and
+   download the latest binary for your operating system.
+2. Unpack the downloaded file then run the binary.
+3. In your browser navigate to `localhost:8443`.
+
+## Usage
+Run `code-server --help` to view available options.
+
+### Encrypting traffic with HTTPS
+To encrypt the traffic between the browser and server use `code-server --cert`
+followed by the path to your certificate. Additionally, you can use certificate
+keys with `--cert-key` followed by the path to your key. If you pass `--cert`
+without any path code-server will generate a self-signed certificate.
+
+You can use [Let's Encrypt](https://letsencrypt.org/) to get an SSL certificate
+for free.
+
+### Nginx Reverse Proxy
+The trailing slashes are important.
+
+```
+server {
+  listen 80;
+  listen [::]:80;
+  server_name code.example.com code.example.org;
+  location /some/path/ { # Or / if hosting at the root.
+      proxy_pass http://localhost:8443/;
+      proxy_set_header Host $host;
+      proxy_set_header Upgrade $http_upgrade;
+      proxy_set_header Connection upgrade;
+      proxy_set_header Accept-Encoding gzip;
+  }
+}
+```
+
+### Apache Reverse Proxy
+```
+<VirtualHost *:80>
+  ServerName code.example.com
+
+  RewriteEngine On
+  RewriteCond %{HTTP:Upgrade} =websocket [NC]
+  RewriteRule /(.*)           ws://localhost:8443/$1 [P,L]
+  RewriteCond %{HTTP:Upgrade} !=websocket [NC]
+  RewriteRule /(.*)           http://localhost:8443/$1 [P,L]
+
+  ProxyRequests off
+
+  RequestHeader set X-Forwarded-Proto https
+  RequestHeader set X-Forwarded-Port 443
+
+  ProxyPass / http://localhost:8443/ nocanon
+  ProxyPassReverse / http://localhost:8443/
+
+</VirtualHost>
+```