Update nano_bm25_subset_config.json

nano_bm25_subset_config.json

@@ -12,6 +12,11 @@
   "selection_candidates": [
     "transformer:qwen",
     "stemmer:pystemmer",
+    "nltk_stem:language-specific nltk stemmer",
+    "nltk_stem_stop:nltk stemmer + language stopwords",
+    "english_porter:nltk+regex",
+    "english_porter_stop:nltk+regex+stopwords",
+    "english_regex:regex",
     "wordseg:ja|zh|th|ko (when dependencies are available)",
     "whitespace:split"
   ],
@@ -461,4 +466,4 @@
       ]
     }
   ]
-}
+}