docs: reflection: built-ins are function values of type builtin (card builtin-functions)
reflection: dir of a list or text includes the builtin methods (card dir-lists)
docs: a function body is code, printing as its source (card body-should)
docs: reflection: function objects, methods(), type(f) with the signature, printed functions (card module-methods)
docs: reflection: doc strings, a function's leading text and the comment above it (card doc-strings)
docs: reflection: help of a module and its words, function(name).dump, a help line prints (cards joinable-error, help-undefined)
reflection: new page (dir, fields, methods, help, function params/signature/dump/effects)