py : update outdated copy-paste instructions [no ci] (ggerganov#10667)

This commit updates the copy-paste instruction in
convert_hf_to_gguf_update.py to reflect that convert_hf_to_gguf.py
will have already been updated with the new get_vocab_base_pre()
function when this script completes.

convert_hf_to_gguf_update.py

@@ -17,7 +17,7 @@
 #
 #   python3 convert_hf_to_gguf_update.py <huggingface_token>
 #
-# - Copy-paste the generated get_vocab_base_pre() function into convert_hf_to_gguf.py
+# - The convert_hf_to_gguf.py script will have had its get_vocab_base_pre() function updated
 # - Update llama.cpp with the new pre-tokenizer if necessary
 #
 # TODO: generate tokenizer tests for llama.cpp