Add users / permissions to docs repo

[ltagliaferri]

Summary

Resolves #300 following discussion in sigstore/docs#43

Release Note

NONE

Documentation

No docs update

[github-actions]

🍹 preview on sigstore-github-sync/sigstore/github-prod

Pulumi report

Previewing update (sigstore/github-prod)

View Live: https://app.pulumi.com/sigstore/sigstore-github-sync/github-prod/previews/582d8432-0add-4a19-8bed-fac8fcfe8e73

@ Previewing update........
pulumi:pulumi:Stack: (same)
[urn=urn:pulumi:github-prod::sigstore-github-sync::pulumi:pulumi:Stack::sigstore-github-sync-github-prod]
+ github:index/repositoryCollaborator:RepositoryCollaborator: (create)
    [urn=urn:pulumi:github-prod::sigstore-github-sync::github:index/repositoryCollaborator:RepositoryCollaborator::docs-smythp]
    permission               : "maintain"
    permissionDiffSuppression: false
    repository               : "docs"
    username                 : "smythp"
+ github:index/repositoryCollaborator:RepositoryCollaborator: (create)
    [urn=urn:pulumi:github-prod::sigstore-github-sync::github:index/repositoryCollaborator:RepositoryCollaborator::docs-jonvnadelberg]
    permission               : "triage"
    permissionDiffSuppression: false
    repository               : "docs"
    username                 : "jonvnadelberg"
@ Previewing update....
Resources:
+ 2 to create
579 unchanged

[haydentherapper]

cc tsc for approval: @trevrosen @bobcallaway @priyawadhwa @lukehinds @SantiagoTorres