Add a minimal README for zoneinfo_rs (#569)

Author: nekevss

zoneinfo/README.md

@@ -0,0 +1,28 @@
+
+# Zoneinfo_rs
+
+**NOTE:** This crate is experimental and should be considered unstable.
+
+`zoneinfo_rs` provides basic parsing and compilation of IANA's time zone database
+zoneinfo files.
+
+```rust
+use std::path::Path;
+use zoneinfo_rs::{ZoneInfoData, ZoneInfoCompiler};
+// Below assumes we are in the parent directory of `tzdata`
+let zoneinfo_filepath = Path::new("./tzdata/");
+let parsed_data = ZoneInfoData::from_zoneinfo_directory(zoneinfo_filepath)?;
+let _compiled_data = ZoneInfoCompiler::new(parsed_data).build();
+```
+
+## Extra notes
+
+Currently, parsing only supports parsing of zoneinfo files and none of the preprocessing
+typically completed by `awk` scripts in tzdata.
+
+It is recommended to still use the baseline awk script until preprocessing is supported.
+
+## IANA tzdb repository
+
+The latest version of the time zone database can be found [here](https://www.iana.org/time-zones)
+