fix link error

[lunaczp]

mising https:// in url, resulting a 404 error

[jackyangjie]

def tokenization(examples):
sources = []
targets = []
for instruction, input_text, output in zip(examples['instruction'],examples['input'],examples['output']):
if input_text is not None and input_text !="":
instruction = instruction+'\n'+input_text
source = system_format.format(content=DEFAULT_SYSTEM_PROMPT) + user_format.format(content=instruction)
target = output

        sources.append(source)
        targets.append(target)

这里 output需要 assistant_format.format(content=output)