test stub hover documentation

src/tests/documentation.v

@@ -6,6 +6,7 @@ fn documentation() testing.Tester {
 	mut t := testing.with_name('documentation')
 
 	t.documentation_test('rendered', 'documentation/rendered.v')
+	t.documentation_test('stubs', 'documentation/stubs.v')
 
 	return t
 }

src/tests/testdata/documentation/stubs.v

@@ -0,0 +1,2 @@
+type Foo = v/*caret*/oidptr
+

src/tests/testdata/documentation/stubs.v.md

@@ -0,0 +1,7 @@
+Module: **stubs**
+```v
+pub type voidptr = voidptr
+```
+
+voidptr is an untyped pointer. You can pass any other type of pointer value, to a function that accepts a voidptr.
+Mostly used for [C interoperability](https://docs.vosca.dev/advanced-concepts/v-and-c.html).