docs(config): make --config <PATH> more prominent

src/bin/cargo/cli.rs

@@ -668,7 +668,7 @@ See '<cyan,bold>cargo help</> <cyan><<command>></>' for more information on a sp
             .action(ArgAction::SetTrue)
             .global(true)
             .hide(true))
-        .arg(multi_opt("config", "KEY=VALUE", "Override a configuration value").global(true))
+        .arg(multi_opt("config", "KEY=VALUE|PATH", "Override a configuration value").global(true))
         // Better suggestion for the unsupported lowercase unstable feature flag.
         .arg( Arg::new("unsupported-lowercase-unstable-feature-flag")
             .help("")

src/doc/src/reference/config.md

@@ -220,10 +220,14 @@ In addition to the system above, Cargo recognizes a few other specific
 
 Cargo also accepts arbitrary configuration overrides through the
 `--config` command-line option. The argument should be in TOML syntax of
-`KEY=VALUE`:
+`KEY=VALUE` or provided as a path to an extra configuration file:
 
 ```console
+# With `KEY=VALUE` in TOML syntax
 cargo --config net.git-fetch-with-cli=true fetch
+
+# With a path to a configuration file
+cargo --config ./path/to/my/extra-config.toml fetch
 ```
 
 The `--config` option may be specified multiple times, in which case the
@@ -232,6 +236,10 @@ that is used when multiple configuration files apply. Configuration
 values specified this way take precedence over environment variables,
 which take precedence over configuration files.
 
+When the `--config` option is provided as an extra configuration file,
+The configuration file loaded this way follow the same precedence rules
+as other options specified directly with `--config`.
+
 Some examples of what it looks like using Bourne shell syntax:
 
 ```console
@@ -251,11 +259,6 @@ cargo --config "target.'cfg(all(target_arch = \"arm\", target_os = \"none\"))'.r
 cargo --config profile.dev.package.image.opt-level=3 …
 ```
 
-The `--config` option can also be used to pass paths to extra
-configuration files that Cargo should use for a specific invocation.
-Options from configuration files loaded this way follow the same
-precedence rules as other options specified directly with `--config`.
-
 ## Config-relative paths
 
 Paths in config files may be absolute, relative, or a bare name without any path separators.