remove stale Brill doctests

nltk/test/tag.doctest

@@ -20,33 +20,3 @@ Add tests for:
     backoff tagger if the backoff tagger gets that context correct at
     *all* locations.
 
-Brill Tagger
-------------
-  - test that fast & normal trainers get identical results when
-    deterministic=True is used.
-  - check on some simple examples to make sure they're doing the
-    right thing.
-
-Make sure that get_neighborhoods is implemented correctly -- in
-particular, given *index*, it should return the indices *i* such that
-applicable_rules(token, i, ...) depends on the value of the
-*index*\ th token.  There used to be a bug where this was swapped --
-i.e., it calculated the values of *i* such that
-applicable_rules(token, index, ...) depended on *i*.
-
-    >>> from nltk.tag.brill import ProximateTokensTemplate, ProximateWordsRule
-    >>> t = ProximateTokensTemplate(ProximateWordsRule, (2,3))
-    >>> for i in range(10):
-    ...     print(sorted(t.get_neighborhood('abcdefghijkl', i)))
-    [0]
-    [1]
-    [0, 2]
-    [0, 1, 3]
-    [1, 2, 4]
-    [2, 3, 5]
-    [3, 4, 6]
-    [4, 5, 7]
-    [5, 6, 8]
-    [6, 7, 9]
-
-