docs: initial README

README.md

@@ -1,5 +1,44 @@
 # tax-ids
 
+TaxIds is a library for validating the syntax and verifying the legitimacy of business tax ids (VAT, GST etc) for various countries.
+
+## Usage
+
+```rust
+use tax_ids::TaxId;
+
+// Instantiate a new TaxId object
+// Raises an ValidationError if the tax id does not follow country syntax
+let tax_id = match TaxId::new("SE556703748501") {
+    Ok(tax_id) => tax_id,
+    Err(e) => println!("ValidationError: {}", e),
+};
+
+// Verify the tax id against the country's tax id database.
+// Raises a VerificationError if the tax id is not legitimate
+match tax_id.verify() {
+    Ok(verified) => println!("Tax id is legitimate: {}", verified),
+    Err(e) => println!("VerificationError: {}", e),
+};
+```
+
+## Installation
+
+With default feature `eu_vat`:
+```toml
+[dependencies]
+tax_ids = "0.1.0"
+```
+
+### Available features
+
+| Feature | Description | Default
+| --- | --- | --- |
+| `eu_vat` | European Union VAT numbers | ✓ |
+| `gb_vat` | United Kingdom VAT numbers |
+| `ch_vat` | Switzerland VAT numbers |
+| `no_vat` | Norway VAT numbers |
+
 ## License
 
 Licensed under either of
@@ -15,4 +54,4 @@ at your option.
 
 Unless you explicitly state otherwise, any contribution intentionally submitted
 for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
-dual licensed as above, without any additional terms or conditions.
+dual licensed as above, without any additional terms or conditions.