docs(result): add section about typechecking

docs/reference/result.md

@@ -45,6 +45,42 @@ modified.
 However, the value inside the `Result` may be mutable, so it is important to be aware
 of this when working with `Result` values.
 
+## Typechecking
+
+The `Result` type aims to be as type-safe as possible, however due to Luau
+limitations or bugs, some areas may not typecheck as expected.
+
+### Callbacks
+
+When calling a function through `:` syntax that takes a callback, the type of the
+parameters aren't inferred.
+
+```lua
+local res = Result.Ok(5)
+local mapped = res:map(function(value)
+  -- ┌────────────────────────── ^^^^^
+  -- └ this is typed as `a` instead of `number`
+  return value * 2
+end)
+```
+
+This can be worked around by calling the function using `.` syntax:
+
+```lua
+local res = Result.Ok(5)
+
+local mapped = Result.map(res, function(value)
+  -- ┌───────────────────────────────── ^^^^^
+  -- └ correctly typed as `number`
+  return value * 2
+end)
+
+-- the following is equivalent
+local mapped = res.map(res, function(value)
+  return value * 2
+end)
+```
+
 ## Static Functions
 
 ### Result.Ok