Implicitly convert strings in type userdata methods that accept a key arg and allow strings as keys in the props table of types.newtable

docs/user-defined-type-function-strings-as-keys.md

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+# Implicitly convert strings in type userdata methods that accept a `key` arg and allow strings as keys in the `props` table of `types.newtable`
+
+## Summary
+
+This RFC proposes allowing strings as keys for methods on the `table` type userdata in type functions, alongside allowing strings as keys instead of types in the `types.newtable` method of the types library.
+
+## Motivation
+
+Currently having to always wrap string literal keys in `types.singleton` is annoying, and becomes especially annoying when using `types.newtable` due to having to write something like the following:
+
+```luau
+types.newtable({
+	[types.singleton("meow")] = types.unknown,
+	[types.singleton("mrrp")] = types.unknown,
+})
+```
+
+Instead of:
+
+```luau
+types.newtable({
+	meow = types.unknown,
+	mrrp = types.unknown,
+})
+```
+
+## Design
+
+As a solution, methods that accept a `key` arg on the table `type` instance, and keys in `props` table passed to `types.newtable` will allow strings. With luau implicitly converting these strings to type userdatas.
+
+### Changed methods
+
+### `types` Library
+
+| Name | Current Type | New Type |
+| ------------- | ------------- | ------------- |
+| `newtable` | (props: {[type]: type \| { read: type, write: type } }?, indexer: { index: type, readresult: type, writeresult: type }?, metatable: type?) -> type | (props: {[type \| string]: type \| { read: type, write: type } }?, indexer: { index: type, readresult: type, writeresult: type }?, metatable: type?) -> type  |
+
+#### Table `type` instance
+
+| Name | Current Type | New Type |
+| ------------- | ------------- | ------------- |
+| `setproperty` | (key: type, value: type?) -> () | (key: type \| string, value: type?) -> () |
+| `setreadproperty` | (key: type, value: type?) -> () | (key: type \| string, value: type?) -> () |
+| `setwriteproperty` | (key: type, value: type?) -> () | (key: type \| string, value: type?) -> () |
+| `readproperty` | (key: type) -> type? | (key: type \| string) -> type? |
+| `writeproperty` | (key: type) -> type? | (key: type \| string) -> type? |
+
+## Drawbacks
+
+Adds implcit behavior, although the behavior is fairly straightforward to understand.
+
+## Alternatives
+
+Add new methods to the types library and on the table type instance for accepting strings as keys, or do nothing.