docs: don't list all attribute types in build-ref
Fixes
Closes
@@ -358,7 +358,7 @@ testdata/input.txt
the <a href='be/overview.html'>Build
Encyclopedia</a> for the full list of supported rules and their
corresponding attributes. Each attribute has a name and a
- type. The full set of types that an attribute can have is: integer,
+ type. Some of the common types an attribute can have are integer,
label, list of labels, string, list of strings, output label,
list of output labels. Not all attributes need to be specified in
every rule. Attributes thus form a dictionary from keys (names) to
