docs: Cross-link root, file_server, php_fastcgi directives (#45)

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

* Minor touch-ups

Co-authored-by: Matthew Holt <mholt@users.noreply.github.com>

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

@@ -4,7 +4,9 @@ title: file_server (Caddyfile directive)
 
 # file_server
 
-A static file server. It works by appending the request's URI path to the [site's root path](/docs/caddyfile/directives/root).
+A static file server. It works by appending the request's URI path to the [site's root path](/docs/caddyfile/directives/root). By default, it enforces canonical URIs; if necessary, requests to directories will be redirected to have a trailing forward slash, and requests to files will be redirected to strip the trailing slash.
+
+Most often, the `file_server` directive is paired with the [`root`](/docs/caddyfile/directives/root) directive to set file root for the whole site.
 
 
 ## Syntax
@@ -19,7 +21,7 @@ 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: This subdirective only changes the root for this directive. 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 this 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 +46,10 @@ Only serve static files out of the `/static` folder:
 ```caddy-d
 file_server /static/*
 ```
+
+The `file_server` directive is usually paired with the [`root` directive](/docs/caddyfile/directives/root) 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 [`root` directive](/docs/caddyfile/directives/root) is often used to specify the directory containing the PHP files:
+
+```caddy-d
+root * /var/www/html
+php_fastcgi 127.0.0.1:9000
+```

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

@@ -8,6 +8,8 @@ Sets the root path of the site, used by various matchers and directives that acc
 
 Specifically, this directive sets the `{http.vars.root}` placeholder. It is mutually exclusive to other `root` directives in the same block, so it is safe to define multiple roots with matchers that intersect: they will not cascade and overwrite each other.
 
+This directive does not automatically enable serving static files, so it is often used in conjunction with the [`file_server` directive](/docs/caddyfile/directives/file_server) or the [`php_fastcgi` directive](/docs/caddyfile/directives/php_fastcgi).
+
 
 ## Syntax
 
@@ -17,28 +19,35 @@ root [<matcher>] <path>
 
 - **&lt;path&gt;** is the path to use for the site root.
 
-Note that a matcher token is usually required since the first argument is a path, which could look like a path matcher.
+Note that the `<path>` argument could be confused by the parser as a [matcher token](/docs/caddyfile/matchers#syntax) if the it begins with `/`. To disambiguate, specify a wildcard matcher token (`*`). See examples below.
 
 ## Examples
 
 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`:
+Change 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
+```