cargo: update description

This crate is not just "more than a safe interface to libc's memchr," it
is literally no longer that at all.

Fixes #138

Cargo.toml

@@ -2,12 +2,15 @@
 name = "memchr"
 version = "2.6.3"  #:version
 authors = ["Andrew Gallant <jamslam@gmail.com>", "bluss"]
-description = "Safe interface to memchr."
+description = """
+Provides extremely fast (uses SIMD on x86_64, aarch64 and wasm32) routines for
+1, 2 or 3 byte search and single substring search.
+"""
 documentation = "https://docs.rs/memchr/"
 homepage = "https://github.com/BurntSushi/memchr"
 repository = "https://github.com/BurntSushi/memchr"
 readme = "README.md"
-keywords = ["memchr", "char", "scan", "strchr", "string"]
+keywords = ["memchr", "memmem", "substring", "find", "search"]
 license = "Unlicense OR MIT"
 exclude = ["/bench", "/benchmarks", "/.github", "/fuzz", "/scripts", "/tmp"]
 edition = "2021"