Readme fixes

[TomMaullin]

What does this PR do?

This PR addresses documentation issues by fixing the reference links, adding citation details and a CITATION.cff file and updating how to check for updates. This PR is review ready

Link to relevant issues

• 74 : README: Examples link to missing pages on nisox.org

• 73 : README: Remove link to snpm_update and link to releases for details on bug and fixes

• 65 : Add citation information

PR submission checklist

• [ ] Run the tests (cf. instructions
• [ ] Copy/paste the test report in a comment below
• [ ] All tests in the test suite pass

Tests were not run as only markdown files have been edited.

[nicholst]

Looks good! When this is merged does this mean we'll have a new release for SnPM?

But first: Really trivial, but can you fix an old typo before merging: In readme.md, can you fix the English in:

two-sample t-test with nscans>12 was errored due to call to undefined

e.g. so it reads

two-sample t-test with nscans>12 caused an error due to call to undefined

[TomMaullin]

Hi @nicholst ,

The english has been fixed as you have suggested! I will make a new release shortly! Is this okay to merge?

[nicholst]

Super! Thank you!