Update site for 2.0; add v2 landing page with asciinema video; docs

src/docs/markdown/caddyfile/directives/reverse_proxy.md

@@ -185,7 +185,7 @@ Set the upstream Host header to the address of the upstream (by default, it will
 
 ```
 reverse_proxy localhost:9000 {
-    header_up Host {http.reverse_proxy.upstream.hostport}
+	header_up Host {http.reverse_proxy.upstream.hostport}
 }
 ```
 
@@ -195,3 +195,11 @@ Reverse proxy to an HTTPS endpoint:
 reverse_proxy https://example.com
 ```
 
+Strip a path prefix then proxy:
+
+```
+route /prefix/* {
+	uri strip_prefix /prefix
+	reverse_proxy localhost:9000
+}
+```

src/docs/markdown/caddyfile/directives/tls.md

@@ -22,6 +22,7 @@ tls [internal|<email>] | [<cert_file> <key_file>] {
 	load      <paths...>
 	ca        <ca_dir_url>
 	ca_root   <pem_file>
+	dns       <provider_name> [<params...>]
 	on_demand
 }
 ```
@@ -59,6 +60,7 @@ tls [internal|<email>] | [<cert_file> <key_file>] {
 - **load** specifies a list of folders from which to load PEM files that are certificate+key bundles.
 - **ca** changes the ACME CA endpoint. This is most often used to use [Let's Encrypt's staging endpoint](https://letsencrypt.org/docs/staging-environment/) or an internal ACME server. (To change this value for the whole Caddyfile, use the `acme_ca` [global option](/docs/caddyfile/options) instead.)
 - **ca_root** specifies a PEM file that contains a trusted root certificate for the ACME CA endpoint, if not in the system trust store.
+- **dns** enables the [DNS challenge](/docs/automatic-https#dns-challenge) using the given provider plugin, which must be from one of the [caddy-dns](https://github.com/caddy-dns) repositories. Each provider plugin may have their own syntax following their name; refer to their docs for details.
 - **on_demand** enables [on-demand TLS](/docs/automatic-https#on-demand-tls) for the hostnames given in the site block's address(es).
 
 
@@ -89,4 +91,12 @@ Specify an email address for your ACME account (but if only one email is used fo
 
 ```
 tls your@email.com
+```
+
+Enable the DNS challenge for a domain managed on Cloudflare with account credentials in an environment variable:
+
+```
+tls {
+	dns cloudflare {env.CLOUDFLARE_API_TOKEN}
+}
 ```