docs/HACKING: Add example for ostree-rs-ext crate development

[travier]

No description provided.

[jmarrero]

lgtm

[travier]

/override fcos-e2e
As this is only a docs change.

[openshift-ci]

@travier: /override requires failed status contexts, check run or a prowjob name to operate on.
The following unknown contexts/checkruns were given:

• fcos-e2e

Only the following failed contexts/checkruns were expected:

• Build
• ci/prow/fcos-e2e
• continuous-integration/jenkins/pr-merge

If you are trying to override a checkrun that has a space in it, you must put a double quote on the context.

In response to this:

/override fcos-e2e
As this is only a docs change.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[travier]

/override ci/prow/fcos-e2e

[openshift-ci]

@travier: Overrode contexts on behalf of travier: ci/prow/fcos-e2e

In response to this:

/override ci/prow/fcos-e2e

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.