Updated command-line usage

[kockan]

New command-line usage with full list of accepted parameters and an example invocation of the command. Also slightly edited the tool description to match the vision of mirroring grep as closely as possible.

[kockan]

I've learned some interesting things from the failed lint check for this, considering I didn't change any code.

It looks like clippy had some updates regarding the useless_vec lint in the latest 1.72.0 version. It shouldn't lint inside macros, but it does, despite being fixed previously: rust-lang/rust-clippy#11094

Here's the problematic part

Compiling fqgrep v1.0.3 (/home/runner/work/fqgrep/fqgrep)
error: useless use of `vec!`
   --> src/main.rs:163:1
    |
163 | / arg_enum! {
164 | |     #[derive(PartialEq, Debug, Clone)]
165 | |     enum Color {
166 | |     Never,
...   |
169 | | }
170 | | }
    | |_^
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#useless_vec
    = note: `-D clippy::useless-vec` implied by `-D warnings`
    = note: this error originates in the macro `arg_enum` (in Nightly builds, run with -Z macro-backtrace for more info)

error: could not compile `fqgrep` (bin "fqgrep") due to previous error
Error: The process '/home/runner/.cargo/bin/cargo' failed with exit code 101

Now, the workflow is actually supposed to run the 1.64.0 toolchain (which passes the checks locally) as it was set in the rust-toolchain.toml, but it instead installs the latest stable toolchain (1.72.0). This, I believe, circles back to another issue in fqtk (fulcrumgenomics/fqtk#23), in which I also believe @nh13 is correct about not using toolchain but I haven't tested it.

Open to suggestions here while I keep investigating.