Bump @polkadot/dev, expand compact description (#263)

packages/util/src/compact/index.ts

@@ -8,7 +8,24 @@ import compactFromU8a from './fromU8a';
 import compactToU8a from './toU8a';
 
 /**
- * @summary Encoding and decoding of parity-codec compact numbers
+ * @description
+ * Encoding and decoding of parity-codec compact numbers. The codec is created
+ * to take up the least amount of space for a specific number. It performs the
+ * same function as Length, however differs in that it uses a variable number of
+ * bytes to do the actual encoding. From the Rust implementation for compact
+ * encoding:
+ *
+ *     0b00 00 00 00 / 00 00 00 00 / 00 00 00 00 / 00 00 00 00
+ * (0 ... 2**6 - 1)    (u8)
+ *     xx xx xx 00
+ * (2**6 ... 2**14 - 1)  (u8, u16)  low LH high
+ *     yL yL yL 01 / yH yH yH yL
+ * (2**14 ... 2**30 - 1)  (u16, u32)  low LMMH high
+ *     zL zL zL 10 / zM zM zM zL / zM zM zM zM / zH zH zH zM
+ * (2**30 ... 2**536 - 1)  (u32, u64, u128, U256, U512, U520) straight LE-encoded
+ *     nn nn nn 11 [ / zz zz zz zz ]{4 + n}
+ *
+ * Note: we use *LOW BITS* of the LSB in LE encoding to encode the 2 bit key.
  */
 export {
   compactAddLength,