Merge #39

39: Add `libgpio`, `libgpiod` and `gpiod` to keywords r=ryankurte a=hellow554

The reason is, that I didn't find this crate until I was very desperate and only stumpled upon it by [this](rust-embedded/wg#46 (comment)) comment.

Even today if I google `rust "libgpiod"` I can't find this place.

I often try to google the c library counterpart together with the keyword rust to see if I can find something that suits my needs. This crate does, however it's not easy to find.

Maybe this PR can be extended to update the `README.md` and mention it there as well.

Co-authored-by: Marcel Hellwig <github@cookiesoft.de>

Author: bors[bot]

Cargo.toml

@@ -7,7 +7,7 @@ homepage = "https://github.com/posborne/rust-gpio-cdev"
 repository = "https://github.com/posborne/rust-gpio-cdev"
 readme = "README.md"
 categories = ["embedded", "hardware-support", "os", "os::unix-apis"]
-keywords = ["linux", "gpio", "gpiochip", "embedded"]
+keywords = ["linux", "gpio", "gpiochip", "embedded", "libgpio", "libgpiod", "gpiod"]
 license = "MIT OR Apache-2.0"
 edition = "2018"