lintcheck: update readme and remove the now redundant readme from clippy-dev

Author: matthiaskrgr

clippy_dev/README.md

@@ -1,7 +1,7 @@
 [package]
 name = "lintcheck"
 version = "0.0.1"
-authors = ["Matthias Krüger <matthias.krueger@famsik.de>"]
+authors = ["The Rust Clippy Developers"]
 edition = "2018"
 
 [dependencies]

lintcheck/Cargo.toml

@@ -1,27 +1,19 @@
-# Clippy Dev Tool
-
-The Clippy Dev Tool is a tool to ease Clippy development, similar to `rustc`s
-`x.py`.
-
-Functionalities (incomplete):
-
-## `lintcheck`
+## `cargo lintcheck`
 
 Runs clippy on a fixed set of crates read from
-`clippy_dev/lintcheck_crates.toml` and saves logs of the lint warnings into the
+`lintcheck/lintcheck_crates.toml` and saves logs of the lint warnings into the
 repo.  We can then check the diff and spot new or disappearing warnings.
 
 From the repo root, run:
 
 ```
-cargo run --target-dir clippy_dev/target --package clippy_dev \
---bin clippy_dev --manifest-path clippy_dev/Cargo.toml --features lintcheck -- lintcheck
+cargo run --target-dir lintcheck/target --manifest-path lintcheck/Cargo.toml
 ```
 
 or
 
 ```
-cargo dev-lintcheck
+cargo lintcheck
 ```
 
 By default the logs will be saved into