docs: exactMatch variable

[sdarwin]

Usage of the setting exactMatch is unclear.

There is an issue entitled "What's the point of exactMatch in multi-runner?" And I keep asking myself this question.

As an attempt to answer, this PR includes documentation which covers multiple cases of both exactMatch: true and exactMatch: false.

• please verify the analysis is correct for each case
• if possible, provide a situation which demonstrates the intended positive use of exactMatch: false. that can be added to the text.
• if the conclusion is ultimately that exactMatch should be enabled, and is recommended, then we might wonder: why is the default setting false

[sdarwin]

Maybe there is another solution.

In the root level module it has a variable:

variable "enable_runner_workflow_job_labels_check_all" {
  description = "If set to true all labels in the workflow job must match the GitHub labels (os, architecture and `self-hosted`). When false if __any__ label matches it will trigger the webhook."
  type        = bool
  default     = true
}

That's used to populate exactMatch.

What could be done in multi-runner is:

• Change all instances of exactMatch to be named enable_runner_workflow_job_labels_check_all. In the module, the examples, javascript source code, everywhere. No exactMatch.
• Set the default to "true".
• Then, remove enable_runner_workflow_job_labels_check_all from some of the multi-runner examples. When multi-runner has dozens of possible variables, they don't all need to be set in an example.
• Document the purpose of enable_runner_workflow_job_labels_check_all with a concrete example. "Imagine this scenario, with these labels, and this workflow. You can see how it would be helpful to disable enable_runner_workflow_job_labels_check_all in this particular circumstance."

[npalm]

@sdarwin thanks for taking the time to improve the docs. Will check your PR in more detail asap. The labels are always confusing. In the meantime I would really appreciate if you have time to have a look at this PR (https://github.com/philips-labs/terraform-aws-github-runner/pull/3633). This PR moves all docs to a docs site. Feel free to make comments.

[sdarwin]

This PR should be reconsidered... See my previous comment, about a suggested strategy.