Add macro trigger to usage example

[andyjessen]

This commit adds macro trigger to mf_isblank usage example.

Issue

Link any related issue(s) in this section.

Intent

Current usage example doesn't invoke the macro.

Implementation

What code changes have been made to achieve the intent.

Checks

• [X] Code is formatted correctly (sasjs lint).
• [ ] Any new functionality has been unit tested.
• [ ] All unit tests are passing (sasjs test).
• [ ] The PR desc or underlying commits follow the Conventional Commit standard

[allanbowe]

@all-contributors - please add @andyjessen for docs

Thanks Andy :-)

[allcontributors[bot]]

@allanbowe

I've put up a pull request to add @andyjessen! :tada:

[allanbowe]

Doc site updated: https://core.sasjs.io/mf__isblank_8sas.html

[github-actions[bot]]

:tada: This PR is included in version 4.48.4 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: