📖 Replace ⚠️ with ⚠️ in Contributing Guidelines documentation

[oscr]

What this PR does / why we need it:

Looks like :warning: isn't rendered in the Contributing Guidelines document (as shown below) so I suggest replacing it with the ⚠️ emoji. As a small side note: the commit message and diff preview look a little odd since Github seems to always render :warning: as ⚠️.

https://cluster-api.sigs.k8s.io/contributing#codebase-and-go-modules

[k8s-ci-robot]

Hi @oscr. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

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.

[killianmuldoon]

Good catch - the base issue here is that this is a dual use document.

We expect users to read it on github (where the warning is rendered correctly) and where it's mirrored in the book (and not rendered correctly).

I don't think it's a big issue - but there are a couple of other instances we could change. @oscr do you mind updating the other occurrences with the emoji instead of the tag?:

cluster-api/docs/book/src/developer/providers/v0.3-to-v0.4.md

Line 21 in 0dd3fbd

## :warning: Go Module changes :warning:

cluster-api/docs/book/src/developer/providers/v0.4-to-v1.0.md

Line 62 in 0dd3fbd

## :warning: LeaderElectionResourceLock change :warning:

[killianmuldoon]

/lgtm

Awesome - thank you!

[oscr]

I don't think it's a big issue - but there are a couple of other instances we could change. @oscr do you mind updating the other occurrences with the emoji instead of the tag?:

Great catch! Thanks @killianmuldoon. I've fixed both.

[sbueringer]

Thx!

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: sbueringer

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [sbueringer]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment