docs: note pre-1.0 versioning policy in CONTRIBUTING

[amondnet]

Adds a short Versioning section to CONTRIBUTING documenting that OpenHWP is pre-1.0 and how release-please derives versions (feat→minor, fix→patch, breaking→minor while 0.x).

This PR's squash commit also carries a Release-As: 0.1.0 trailer to force the initial release version: release-please bootstraps the first release of a 0.0.0 project to 1.0.0 by default, which is wrong for a Phase 1 scaffold. The trailer is one-shot (unlike a persistent release-as config), so after 0.1.0 is cut, future versions compute normally. Once merged, release-please updates release PR #2 from 1.0.0 → 0.1.0.

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Summary by cubic

Add a Versioning section to CONTRIBUTING that explains our pre‑1.0 policy and how release-please maps Conventional Commits (feat→minor, fix→patch, breaking→minor in 0.x). Also set the initial release to 0.1.0 so we don’t auto‑bootstrap to 1.0.0.

^{Written for commit fef39ec. Summary will update on new commits.}

[greptile-apps]

Greptile Summary

Adds contributor documentation describing OpenHWP’s pre-1.0 versioning policy.

• Explains how feature, fix, and breaking-change commits affect 0.x versions.
• Clarifies that the project will move to 1.0.0 intentionally.

Confidence Score: 5/5

The PR appears safe to merge with no actionable issues identified.

The documentation-only change describes the repository’s pre-1.0 release policy without altering runtime, build, or release configuration.

Important Files Changed

Filename	Overview
CONTRIBUTING.md	Adds a concise Versioning section consistent with the repository’s configured pre-major release policy.

_{Reviews (1): Last reviewed commit: "docs: note pre-1.0 versioning policy in ..." | Re-trigger Greptile}