DOC: Docstring for comparison operators has "=!" instead of "!="

[daytonb]

Location of the documentation

Shows up in all the flexible comparison docstrings like "https://pandas.pydata.org/docs/dev/reference/api/pandas.DataFrame.ne.html". The typo is in the _flex_comp_doc_FRAME shared docstring found in core/ops/docstrings.py.

Documentation problem

The docstring says =! instead of != for the not-equals comparison.

Suggested fix for documentation

Just need to change it to !=.

[daytonb]

take

[MarcoGorelli]

From a comment on the PR #36077 (comment):

So this change actually breaks building docs, at least using sphinx. Leads to an error

/usr/local/lib/python3.8/site-packages/docutils/nodes.py", line 567, in __getitem__
    return self.attributes[key]
KeyError: 'reftarget'

whereas simply swapping them back fixes the problem. Any idea what might be going on here?

I haven't yet looked into it, just reopening so it's not forgotten

[jbrockmendel]

@MarcoGorelli is there anything left to do here?

[daytonb]

@jbrockmendel and @MarcoGorelli, I don't believe there is anything left to do here. I was pretty certain that my tiny docstring correction could not have broken building the docs and my commit has been part of the main line for quite a while now including several pandas releases. This tells me that whatever was actually causing the doc build failures has also been addressed by some other work.