adds readme; tweak code example

Cargo.toml

@@ -1,12 +1,13 @@
 [package]
 name = "const-crc32"
-version = "1.0.0"
+version = "1.0.1"
 edition = "2021"
 authors = ["Jonathan Strong <jstrong@shipyard.rs>"]
 license = "MIT"
 description = "A `const fn` implementation of crc32 checksum algorithm"
 repository = "https://git.shipyard.rs/jstrong/const-crc32"
 keywords = ["checksum", "crc", "crc32", "const"]
+readme = "README.md"
 
 [dev-dependencies]
 crc32fast = "1.2"

README.md

@@ -0,0 +1,17 @@
+# const-crc32
+
+A `const fn` crc32 checksum implementation.
+
+## Examples
+
+```rust
+const BYTES: &[u8] = "The quick brown fox jumps over the lazy dog".as_bytes();
+const CKSUM: u32 = const_crc32::crc32(BYTES);
+assert_eq!(CKSUM, 0x414fa339_u32);
+```
+
+## Usage
+
+This is a naive implementation that should be expected to have poor performance
+if used on dynamic data at runtime. Usage should generally be restricted to declaring
+`const` variables based on `static` or `const` data available at build time.

src/lib.rs

@@ -4,7 +4,8 @@
 //!
 //! ```
 //! const BYTES: &[u8] = "The quick brown fox jumps over the lazy dog".as_bytes();
-//! assert_eq!(const_crc32::crc32(BYTES), 0x414fa339_u32);
+//! const CKSUM: u32 = const_crc32::crc32(BYTES);
+//! assert_eq!(CKSUM, 0x414fa339_u32);
 //! ```
 
 /// typically crc32 implementations set up a [u32; 256] lookup table. this computes