Explain flags missing in cargo check in --help

This commit closes rust-lang#7389. As stated in the issue, `cargo clippy --help`
provides explanation for some flags and states that the rest are same
as in `cargo check --help`, even though some clippy specific flags
exist.

This commit extends the `cargo clippy --help` with two additional flags,
  - `cargo clippy --fix`
  - `cargo clippy --no-deps`

If there are more flags which are not present in `cargo check --help`
please bring these to my attention, I will include these aswell.
For now, I noticed only the two flags mentioned above.

Author: nfejzic

src/main.rs

@@ -14,6 +14,8 @@ Usage:
     cargo clippy [options] [--] [<opts>...]
 
 Common options:
+    --fix                    Automatically apply lint suggestions
+    --no-deps                Run Clippy only on the given crate
     -h, --help               Print this message
     -V, --version            Print version info and exit