changelog: Add entry about evmc_load_and_configure()
## [6.3.0] - unreleased
+- Added: [[#313](https://github.com/ethereum/evmc/pull/313)]
+ The loader module introduces standardized EVMC module configuration string
+ which contains path to the module and additional options.
+ E.g. `./modules/vm.so,engine=compiler,trace,verbosity=2`.
+ A VM can be loaded, created and configured atomically with
+ new `evmc_load_and_configure()` function.
- Changed: [[#293](https://github.com/ethereum/evmc/pull/293)]
In C++ API `evmc::result::raw()` renamed to `evmc::result::release_raw()`.
- Changed: [[#311](https://github.com/ethereum/evmc/pull/311)]
