Updated changelog

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Release v0.4.0 (Under Development)
 
+* Implemented new 64-bit instruction encoding scheme that is simpler and more efficient. String data is no longer embedded in the instruction stream, ensuring constant instruction length of 8 bytes.
+* Merged `lug::program_encoder` and `lug::rule_encoder` into the `lug::encoder` base class after overhauling how choice/jump offsets are calculated, significantly reducing binary size bloat.
 * Extracted common base class of `lug::basic_parser` into `lug::parser_base` to reduce template bloat.
 * Reduced template bloat for parser directives (improving compiler error messages) and optimized nested directives.
 * Merged parser stack frames together into a single stack using `std::variant`.