docs: NIP13

README.md

@@ -20,6 +20,7 @@ flutter pub add nostr
 - [x] [NIP 05 Mapping Nostr keys to DNS-based internet identifiers](https://github.com/nostr-protocol/nips/blob/master/05.md)
 - [x] [NIP 09 Event Deletion Request](https://github.com/nostr-protocol/nips/blob/master/09.md)
 - [x] [NIP 10 Conventions for clients' use of e and p tags in text events](https://github.com/nostr-protocol/nips/blob/master/10.md)
+- [x] [NIP 13 Proof of Work](https://github.com/nostr-protocol/nips/blob/master/13.md)
 - [x] [NIP 15 End of Stored Events Notice](https://github.com/nostr-protocol/nips/blob/master/15.md)
 - [x] [NIP 19 bech32-encoded entities](https://github.com/nostr-protocol/nips/blob/master/19.md)
 - [x] [NIP 20 Command Results](https://github.com/nostr-protocol/nips/blob/master/20.md)

lib/src/nips/nip_013.dart

@@ -1,6 +1,20 @@
 import 'dart:math';
 
+/// Proof of Work (NIP-13)
+///
+/// NIP-13 introduces Proof of Work (PoW) for nostr notes to deter spam. PoW is validated by counting the number of leading zero bits in a note's ID (difficulty).
+///
+/// Example:
+/// An ID `000000000e9d97a1ab09fc381030b346cdd7a142ad57e6df0b46dc9bef6c7e2d` has a difficulty of `36` with 36 leading zero bits.
+///
+/// Mining involves generating an ID with a desired difficulty by iteratively modifying a `nonce` tag.
 class Nip13 {
+  /// Calculates the number of leading zero bits in a hexadecimal string.
+  ///
+  /// ```dart
+  /// int difficulty = Nip13.countLeadingZeroes("000000000e9d97a1ab09fc381030b346cdd7a142ad57e6df0b46dc9bef6c7e2d");
+  /// print(difficulty); // 36
+  /// ```
   static int countLeadingZeroes(String hex) {
     int count = 0;
     for (int i = 0; i < hex.length; i++) {