Improving the tensor API documentation

[diptorupd]

The sphinx html generated from the docstring for tensor functions is a bit weird. The "->" in the description looks awkward and seems like a typo. Is it the intended rendering? E.g.,

broadcast_to()	-> usm_ndarray Broadcast an array to a new shape; returns the broadcasted array as a view.

I suggest that the "->" be taken out.

[diptorupd]

The issue stems from how dpctl's documentation generation script extracts the summary line from a docstring in case a signature is specified.

The following logic is the culprit: generate_rst.py:

dpctl/docs/generate_rst.py

Line 378 in 8f828f2

def _get_doc_summary(obj):

The function assumes that the closing parenthesis signifies the end of the signature and does not check for an -> followed by the return type.