Correct file argument name in KeyedVectors.save docstring

[hammad7]

Fixes issue : #3528

Just a documentation update for filename argument for KeyedVectors.save() . The argument wasn't updated in the docs when it was changed in the parent class utils.SaveLoad from fname to fname_or_handle . Tested with code:

from gensim.models import KeyedVectors

# Create a KeyedVectors object
model = KeyedVectors(100)

# Attempt to save the model using the incorrect parameter name
try:
    model.save(fname_or_handle="my_model.kv")  ### fname gives error
except TypeError as e:
    print(e)

[mpenkov]

Thank you @hammad7 !