Offer SIGs the ability to schedule messages for announcing when a SIG meeting is happening #42
Description
To make it easier for new contributors to know when a SIG meeting is happening and connect Slack with SIGs we can offer contributors the ability to create a workflow for them to remind contributors when this is happening.
An example of this can be seen on the Collector SIG #otel-collector-dev Slack channel, there are also other SIGs that use a similar mechanism.