docs: Cross-link the root directive with file_server/php_fastcgi

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

@@ -19,7 +19,7 @@ file_server [<matcher>] [browse] {
 ```
 
 - **browse** enables file listings for requests to directories that do not have an index file.
-- **root** sets the path to the site root for just this file server instance, overriding any other. Default: `{http.vars.root}` or the current working directory. Note: When specified as a subdirective like this, only this directive will know this root; for other directives (like [try_files](/docs/caddyfile/directives/try_files) or [templates](/docs/caddyfile/directives/templates)) to know the same site root, use the [root](/docs/caddyfile/directives/root) directive, not subdirective.
+- **root** sets the path to the site root for just this file server instance, overriding any other. Default: `{http.vars.root}` or the current working directory. Note: When specified as a subdirective like this, only this directive will know this root; for other directives (like [`try_files`](/docs/caddyfile/directives/try_files) or [`templates`](/docs/caddyfile/directives/templates)) to know the same site root, use the [`root`](/docs/caddyfile/directives/root) directive, not subdirective.
 - **hide** is a list of files to hide; if requested, the file server will pretend they do not exist. The active configuration file will be added by default.
 - **index** is a list of filenames to look for as index files. Default: `index.html index.txt`
 - **<template_file>** is an optional custom template file to use for directory listings.
@@ -44,3 +44,10 @@ Only serve static files out of the `/static` folder:
 ```caddy-d
 file_server /static/*
 ```
+
+The `file_server` directive is usually paired with the [`root`](/docs/caddyfile/directives/root) directive to set the root path from which to serve files
+
+```caddy-d
+root * /home/user/public_html
+file_server
+```

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

@@ -79,3 +79,10 @@ When using php-fpm listening via a unix socket:
 ```caddy-d
 php_fastcgi unix//run/php/php7.4-fpm.sock
 ```
+
+The `php_fastcgi` directive is usually paired with the [`root`](/docs/caddyfile/directives/root) directive to set the root path from which to serve PHP files
+
+```caddy-d
+root * /var/www/html
+php_fastcgi 127.0.0.1:9000
+```

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

@@ -23,22 +23,29 @@ Note that a matcher token is usually required since the first argument is a path
 
 Set the site root to `/home/user/public_html` for all requests:
 
+(Note that a [wildcard matcher](/docs/caddyfile/matchers#wildcard-matchers) is required here because the first argument is ambiguous with a [path matcher](/docs/caddyfile/matchers#path-matchers).)
+
 ```caddy-d
 root * /home/user/public_html
 ```
 
-(A [wildcard matcher](/docs/caddyfile/matchers#wildcard-matchers) is required in this case because the first argument is ambiguous with a [path matcher](/docs/caddyfile/matchers#path-matchers).)
-
 Set the site root to `public_html` (relative to current working directory) for all requests:
 
+(No matcher token is required here because our site root is a relative path, so it does not start with a forward slash and thus is not ambiguous.)
+
 ```caddy-d
 root public_html
 ```
 
-(No matcher token is required here because our site root is a relative path, so it does not start with a forward slash and thus is not ambiguous.)
-
 Set the site root only for requests in `/foo`:
 
 ```caddy-d
 root /foo/* /home/user/public_html/foo
 ```
+
+The `root` directive is commonly paired with [`file_server`](/docs/caddyfile/directives/file_server) to serve static files and/or with [`php_fastcgi`](/docs/caddyfile/directives/php_fastcgi) to serve a PHP site:
+
+```caddy-d
+root * /home/user/public_html
+file_server
+```