Update 'Blind Type Definitions'

Blind-Type-Definitions.md

@@ -0,0 +1,9 @@
+```
+type ro Pixel U32
+```
+
+"Blind" type definitions are called that because they cannot do fancy things
+like define new members on the type they inherit, but they can inherit from
+primitive types, pointers, and arrays. This can be useful for adding extra
+semantics to code, and for defining methods on things that don't need to be a
+whole object.