class Walker:

    def __init__(self, doc):
        self.document = doc
self.fields = {}

def dispatch_visit(self, x):
    if isinstance(x, docutils.nodes.field):
        field_name = x.children[0].rawsource
field_value = x.children[1].rawsource
self.fields[field_name] = field_value
w = Walker(doctree)
doctree.walk(w)
pprint.pprint(w.fields)
Извлечь список полей из reStructuredText