update readme

README.md

@@ -2,6 +2,61 @@
 
 **git-config is a library for interacting with `git-config` files.**
 
+This crate intents to be a performant Rust implementation for reading and
+writing `git-config` files. It exposes tiers of abstractions, from simple
+config value wrappers to a high level reader and writer.
+
+The highlight of this crate is the zero-copy parser. We employ techniques to
+avoid copying where necessary, and reads that do not need normalization are
+guaranteed to be zero-copy. Higher level abstractions maintain this guarantee,
+and utilizes acceleration structures for increased performance.
+
+Currently, this is _not_ a binary. While we do intent to have a drop-in
+replacement for the `git config` sub-command, we're currently missing
+system-level abstractions to do so.
+
+## Examples
+
+Reading and writing to a config:
+
+```rust
+use git_config::file::GitConfig;
+use git_config::values::Boolean;
+use std::fs::read_to_string;
+
+let input = read_to_string(r#"
+[core]
+  some-bool = true
+
+[other "internal"]
+  hello = world
+"#)?;
+let mut config = GitConfig::from(input)?;
+let boolean = config.get_config::<Boolean>("core", None, "some-bool");
+config.set_value("other", Some("internal"), "hello", "clippy!");
+```
+
+## Contributing
+
+Contributions are always welcome!
+
+### Code quality
+
+This repository enables pedantic, cargo, and nursery `clippy` lints. Make sure
+to run `cargo clean && cargo clippy` (the clean stage is very important!) to
+ensure your code is linted.
+
+### Testing
+
+Since this is a performance oriented crate, in addition to well tested code via
+`cargo test`, we also perform benchmarks to measure notable gains or losses in
+performance. We use [`criterion`] so benches can be run via `cargo bench` after
+installing it via `cargo install cargo-criterion`.
+
+Changes to `parser.rs` may include a request to fuzz to ensure that it cannot
+panic on inputs. This can be done by executing `cargo fuzz parser` after
+installing the `fuzz` sub-command via `cargo install cargo-fuzz`.
+
 #### License
 
 <sup>
@@ -16,3 +71,5 @@ Unless you explicitly state otherwise, any contribution intentionally submitted
 for inclusion in git-config by you, as defined in the Apache-2.0 license, shall
 be dual licensed as above, without any additional terms or conditions.
 </sub>
+
+[`criterion`]: https://github.com/bheisler/criterion.rs