Add basic documentation.

source/lib.rs

@@ -1,3 +1,28 @@
+//! # gravatar-rs
+//!
+//! This crate provides an API for creating [Gravatar image URLs], and by
+//! extension, [Ivatar/Libravatar image URLs].
+//!
+//! [Gravatar image URLs]: https://gravatar.com/site/implement/images/
+//! [Ivatar/Libravatar image URLs]: https://wiki.libravatar.org/api/
+//!
+//! The default [`Generator::base_url`] is `www.gravatar.com`, if you want to
+//! set a custom `base_url` use [`Generator::set_base_url`].
+//!
+//! ```rust
+//! use gravatar_rs::Generator;
+//!
+//! let generator = Generator::default();
+//!
+//! let gravatar_url = generator.generate("helllo@holllo.cc");
+//!
+//! assert_eq!(
+//!   gravatar_url,
+//!   "https://www.gravatar.com/avatar/ebff9105dce4954b1bdb57fdab079ff3"
+//! );
+//! ```
+
+/// A generator for Gravatar image URLs.
 #[derive(Debug)]
 pub struct Generator {
   pub base_url: String,
@@ -12,11 +37,28 @@ impl Default for Generator {
 }
 
 impl Generator {
+  /// Hashes an email with [`md5`] according to the [Gravatar hashing steps].
+  ///
+  /// ```rust
+  /// use gravatar_rs::Generator;
+  ///
+  /// let hash = Generator::hash_email("helllo@holllo.cc");
+  ///
+  /// assert_eq!(
+  ///   hash,
+  ///   "ebff9105dce4954b1bdb57fdab079ff3"
+  /// );
+  /// ```
+  ///
+  /// [Gravatar hashing steps]: https://en.gravatar.com/site/implement/hash/
   pub fn hash_email(email: &str) -> String {
     let hash = md5::compute(email.trim().to_lowercase());
     format!("{hash:x}")
   }
 
+  /// Generates a new Gravatar image URL using the Generator's configuration.
+  ///
+  /// See the top-level module documentation for examples.
   pub fn generate(&self, email: &str) -> String {
     let base_url = &self.base_url;
     let hash = Self::hash_email(email);
@@ -24,6 +66,14 @@ impl Generator {
     format!("https://{base_url}/avatar/{hash}")
   }
 
+  /// Configures the Generator to use the base URL for generated URLs.
+  ///
+  /// ```rust
+  /// use gravatar_rs::Generator;
+  ///
+  /// // Use Libravatar instead of Gravatar.
+  /// Generator::default().set_base_url("cdn.libravatar.org");
+  /// ```
   pub fn set_base_url(self, base_url: &str) -> Self {
     Self {
       base_url: base_url.to_string(),