Fix URL in comment for contrastive loss function (#24271)
* Update language_modeling.py
in "class TextDatasetForNextSentencePrediction(Dataset)", double considering "self.tokenizer.num_special_tokens_to_add(pair=True)"
so, i remove self.block_size, and add parameter for "def create_examples_from_document". like "class LineByLineWithSOPTextDataset" do
* Update language_modeling.py
* Fix URL in comment for contrastive loss function
