rfc: Exports by value are const

rfcx/exports-by-values-are-const.md

@@ -0,0 +1,28 @@
+# Feature name
+
+FFlag: LuauExportsAreConst
+
+## Summary
+
+Amends the export-by-value RFC described in [Luau RFC #179](<https://github.com/luau-lang/rfcs/pull/179>) making all exports-by-value constant, removing the `export local` syntax and with it marking exports as mutable.
+
+## Motivation
+
+Exports-by-value should not be mutable. First and foremost, it greatly simplifies any optimizations which utilize exports-by-value, and secondly removes the objectively ugly syntax of `export local`.
+
+## Design
+
+Exports-by-value are now only declared via the syntax of
+```luau
+export variable_name[: type] = value
+```
+instead of optionally accepting the `local` keyword to signify that they're mutable by the module in which they're declared prior to them being returned at the end of the file.
+This makes all exports-by-value constant with no way to change it.
+
+## Drawbacks
+
+Breaks backwards compatibility with any code that utilizes `export local`.
+
+## Alternatives (optional)
+
+Not doing this.