* fix: force symbol resolution for types that serde de/serializes
Force symbols into scope when mixins are used with generic overloads. When mixins are used with generic overloads, the overloaded symbols in scope of the mixin are evaluated from the perspective of the mixin. This creates issues in downstream modules that may inadvertantly dispatch *only* to the symbols in the scope of the mixin, even when the module with the wrong symbol overloads is not imported. By forcing the compiler to use symbols for types handled by serde, we can be sure that these symbols are available to downstream modules. We can also be sure that these `fromJson` symbols can be overloaded where needed.
* remove enum forced scoping
Forcing a scoping for a particular enum type would only resolve that type and not all enum types.
* Add mixin + generic overloads as known issue to README
* try to fix URL reference to deserializer.nim
* Change parseJson to JsonNode.parse
Exporting `parseJson` causes symbol clashes in downstream repos that import std/json, so changing the signature completely avoid this clash.
* Fix usages of parseJson, update README
Eric