message: Documentation fix - use '_' instead of '.' in the type alias example.
diff: @@ -540,13 +540,13 @@ names are reserved for [dialect-specific types](#dialect-specific-types).
  Example:
  ```mlir {.mlir}
  -!avx.m128 = type vector<4 x f32>
  +!avx_m128 = type vector<4 x f32>
  // Using the original type.
  "foo"(%x) : vector<4 x f32> -> ()
  // Using the type alias.
  -"foo"(%x) : !avx.m128 -> ()
  +"foo"(%x) : !avx_m128 -> ()
  ```
  ### Builtin Types
  