match_string description update

[joeflack4]

Updates

Update sssom_schema.yaml

• Updated description for match_string. Corrected plurality issue.

PR boilerplate

Apologies, skipping this because this is a very small issue / PR.

Boilerplate

Resolves [#ISSUE, #ISSUE]

• docs/ have been added/updated if necessary
• make test has been run locally
• tests have been added/updated (if applicable)
• CHANGELOG.md has been updated.

If you are proposing a change to the SSSOM metadata model, you must

• provide a full, working and valid example in examples/
• provide a link to the related GitHub issue in the see_also field of the linkml model
• provide a link to a valid example in the see_also field of the linkml model

[Add a description, mentioning at least relevant #ISSUE and how it was addressed. A bulleted list of all changes performed by the PR is is helpful.]

[matentzn]

Thank you for driving by.