OpenCoarrays: remove maintainer, update descrip.

[Dave-Allured]

• Switch from inactive maintainer, to nomaintainer.
• Update the long_description.

Per upstream:
https://github.com/sourceryinstitute/opencoarrays/blob/2.9.2/INSTALL.md#macos

"MacPorts: An unmaintained OpenCoarrays Portfile exists for the MacPorts package manager. Although the current OpenCoarrays contributors have no plans to update the portfile, new contributors are welcome to asssume the port maintainer role and to submit a pull request to update this INSTALL.md file."

Type(s)

• bugfix
• enhancement
• security fix

Tested on

• Not tested. Comment fixes only.

Verification

Have you

• followed our Commit Message Guidelines?
• squashed and minimized your commits?
• checked that there aren't other open pull requests for the same change?
• referenced existing tickets on Trac with full URL?
• checked your Portfile with port lint --nitpick?
• tried existing tests with sudo port test?
• tried a full install with sudo port -vst install?
• tested basic functionality of all binary files?