docs(setup): note nltk punkt_tab download is likely redundant

unstructured already lazily downloads punkt_tab on first tokenize call,
so the eager post-install download is probably duplicate work. Keep it
as a safety net (and to front-load the network hit at install time
instead of on the first office-document parse), but document it.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: thiswillbeyourgithub

setup.py

@@ -70,6 +70,10 @@ def run(self):
                 )
 
         # do "import nltk ; nltk.download('punkt_tab')"
+        # Likely redundant: `unstructured` (our only nltk consumer, via
+        # unstructured.nlp.tokenize) already lazily runs nltk.download("punkt_tab")
+        # on first use. Kept as a safety net so the download happens at install
+        # time rather than on the first parse of an office document.
         try:
             import nltk