Auto merge of rust-lang#12218 - jhpratt:manifest-options-doc, r=blyxyas

Document manifest options

All built-in cargo commands have this output included when run with `cargo foo --help`. Clippy is the only exception, so I have copied the text here. As far as I can tell, the flags come from Cargo itself and not clippy, but the user almost certainly does not care about that.

```text
Manifest Options:
      --manifest-path <PATH>  Path to Cargo.toml
      --frozen                Require Cargo.lock and cache are up to date
      --locked                Require Cargo.lock is up to date
      --offline               Run without accessing the network
```

changelog: Add the standard Manifest Options section to the `--help` output

Author: bors

src/main.rs

@@ -174,8 +174,13 @@ To allow or deny a lint from the command line you can use <cyan,bold>cargo clipp
 You can use tool lints to allow or deny lints from your code, e.g.:
 
     <yellow,bold>#[allow(clippy::needless_lifetimes)]</>
-"
-    )
+
+<green,bold>Manifest Options:</>
+    <cyan,bold>--manifest-path</> <cyan><<PATH>></>  Path to Cargo.toml
+    <cyan,bold>--frozen</>                Require Cargo.lock and cache are up to date
+    <cyan,bold>--locked</>                Require Cargo.lock is up to date
+    <cyan,bold>--offline</>               Run without accessing the network
+")
 }
 #[cfg(test)]
 mod tests {