Update citation information

[freddyheppell]

Created this PR at Ian's request.

• Updated the suggested citation in all the places I could find it (repo README, latest docs README, about page) to suggest citing the demo paper. I've also added a more prominent link to Zenodo.
• In CITATION.cff I've added the paper as the preferred-citation. GitHub will show this citation instead, and it semantically indicates it's a related but different work (preserving all the top-level information about the software itself). As far as I can tell this is the only way to alter the GitHub Cite this Repository tool - it's not possible to show both a code and paper option.
• Remove the README version check/update from version.py, since the GitHub URL citation including has been removed

I tried to get GitHub's generated bibtex to match ACL Anthology's, but I can't get it to show the address field with the conference's location. I believe this is the only field that's commonly displayed that's different.

[github-actions]

Jest Coverage

File	% Stmts	% Branch	% Funcs	% Lines	Uncovered Line #s
All files	83.8	83.96	64	83.8

File	% Stmts	% Branch	% Funcs	% Lines	Uncovered Line #s
All files	83.8	83.96	64	83.8
_jrpc	94.11	91.66	83.33	94.11
_ index.js	94.11	91.66	83.33	94.11	29-30,38-40
_utils	81.97	82.97	57.89	81.97
_ annotations.js	97.72	73.91	100	97.72	35-36
_ dict.js	88.88	83.33	100	88.88	3-4
_ expressions.js	80.08	82.35	80	80.08	...7-98,126-128,139-156,188-190,201-218
_ index.js	73.6	100	14.28	73.6	9-17,28-29,43-53,64-65,76-82,93-94

[twinkarma]

The changes look good, thanks @freddyheppell !

[ianroberts]

Thanks @twinkarma - I've merged to dev but I guess we also need to merge dev to master to get the updated readme to show on the GitHub repo homepage. There's no changes to the actual software so no need for another actual release.