docs: add CONTRIBUTING.md to sig-network

Signed-off-by: Shane Utt <shaneutt@linux.com>

sig-network/CONTRIBUTING.md

@@ -0,0 +1,55 @@
+# Contributing on SIG Network
+
+Welcome!
+
+Thank you for your interest in contributing to SIG Network. Here we cover all
+things networking within and around Kubernetes clusters. This SIG covers a lot
+of ground, see our [charter] and our [README.md] for more details. If you get
+stuck please feel free to reach out for help in our `#sig-network` channel on
+[Kubernetes Slack]!
+
+[charter]:/sig-network/charter.md
+[README.md]:/sig-network/README.md
+[Kubernetes Slack]:https://kubernetes.slack.com
+
+## For Kubernetes Code Contributions
+
+See the [Kubernetes Contributor Guide].
+
+[Kubernetes Contributor Guide]:https://github.com/kubernetes/community/tree/master/contributors/guide#contributor-guide
+
+### For Enhancements
+
+Firstly find out [if your thing is an enhancement].
+
+Once you're sure your thing is in fact an enhancement, you can follow the
+[standard Kubernetes Enhancement Proposal (KEP) procedures][kep].
+
+> **Note**: This process can be a huge time investment and you should deeply
+> consider that before you start the process. Depending on what it is, it can
+> _potentially take years to achieve_.
+
+[if your thing is an enhancemment]:https://github.com/kubernetes/enhancements/?tab=readme-ov-file#is-my-thing-an-enhancement
+[kep]:https://github.com/kubernetes/enhancements/blob/master/keps/README.md
+
+#### Important: Additional "getting started" guidance
+
+In SIG Network we _highly_ recommend staying away from "How will this be
+implemented?" at first. Instead, focus on these things first:
+
+- **"What?"**: What is this at a high level? Without getting into implementation
+  details, what does it achieve? What are the goals?
+- **"Why?"**: Why do we need this? What motivates this? Is this generally
+  applicable?
+- **"Who?"**: Who else in the community needs this? Who can join us in making
+  this KEP a success?
+
+> **Note**: Ultimately the "Who?" is an extremely important question. If you
+> have 1 or more (ideally at least 2) other community members who are on board
+> and can help you move the KEP forward, this can be a tremendous boon.
+
+Get consensus on the "What?", "Why?" and "Who?" first, avoiding discussion of
+"How?" it can be done (if feasible) until there's broad consensus that we have
+the appropriate goals and motivation covered to do it. Join us in the community
+and discuss your ideas ahead of time!
+

sig-network/annual-report-2024.md

@@ -180,7 +180,7 @@ Webinars:
 
 Operational tasks in [sig-governance.md]:
 - [x] [README.md] reviewed for accuracy and updated if needed
-- [ ] [CONTRIBUTING.md] reviewed for accuracy and updated if needed
+- [x] [CONTRIBUTING.md] reviewed for accuracy and updated if needed
 - [x] Other contributing docs (e.g. in devel dir or contributor guide) reviewed for accuracy and updated if needed
 - [x] Subprojects list and linked OWNERS files in [sigs.yaml] reviewed for accuracy and updated if needed
 - [x] SIG leaders (chairs, tech leads, and subproject leads) in [sigs.yaml] are accurate and active, and updated if needed