Document a few gotchas

README.md

@@ -10,6 +10,21 @@ This grammar is able to parse the entire Gleam language. It is largely based
 on the Gleam parser itself, and deviations from that are noted throughout the
 codebase.
 
+Various Gotchas
+---------------
+
+There are a few nodes in the generated AST that may be confusing at first:
+- `type` :: A very ambiguous name, but this refers to a concrete type such as
+  `List(#(String, Int))`
+- `type_name` :: Refers to essentially the left side of a type declaration, and
+  includes parameters, e.g. `MyType(foo, bar)`.
+- `type_identifier` :: Known in the parser as "UpName", this is what you would
+  intuitively think of as a type's name, such as `List` or `Result`.
+
+This is not a comprehensive list. If you find a node confusing, search for it
+in `grammar.js`, as it might have an explanatory comment. Either way, feel free
+to add it to this list and send a PR! ✨
+
 ## DONE
 
 - [x] Parsing