Document that preprocessing.strip_punctuation is limited to ASCII (#2964

)

* Clarifying strip_punctuation limited to ASCII

Add ASCII as qualification on `strip_punctuation` doc string. 
This is "option 1" fix for issue #2962

* Added code comment pointing to issue 2962

Code comment added linking to issue #2962 as a reminder of enhancement possibilities.

* update CHANGELOG.md

Co-authored-by: Michael Penkov <misha.penkov@gmail.com>

CHANGELOG.md

@@ -26,7 +26,7 @@ Changes
 * [#3141](https://github.com/RaRe-Technologies/gensim/pull/3141): Update link for online LDA paper, by [@dymil](https://github.com/dymil)
 * [#3148](https://github.com/RaRe-Technologies/gensim/pull/3148): Fix broken link in documentation, by [@rohit901](https://github.com/rohit901)
 * [#3155](https://github.com/RaRe-Technologies/gensim/pull/3155): Correct parameter name in documentation of fasttext.py, by [@bizzyvinci](https://github.com/bizzyvinci)
-
+* [#2964](https://github.com/RaRe-Technologies/gensim/pull/2964): Document that preprocessing.strip_punctuation is limited to ASCII, by [@sciatro](https://github.com/sciatro)
 ## 4.0.1, 2021-04-01
 
 Bugfix release to address issues with Wheels on Windows:

gensim/parsing/preprocessing.py

@@ -94,7 +94,7 @@ def remove_stopwords(s):
 
 
 def strip_punctuation(s):
-    """Replace punctuation characters with spaces in `s` using :const:`~gensim.parsing.preprocessing.RE_PUNCT`.
+    """Replace ASCII punctuation characters with spaces in `s` using :const:`~gensim.parsing.preprocessing.RE_PUNCT`.
 
     Parameters
     ----------
@@ -115,6 +115,7 @@ def strip_punctuation(s):
 
     """
     s = utils.to_unicode(s)
+    # For unicode enhancement options see https://github.com/RaRe-Technologies/gensim/issues/2962
     return RE_PUNCT.sub(" ", s)