docs: add PATH note for Go installation

[Mohit-001-hash]

What

Added a note to the Go installation section of the README explaining that the Go binary directory must be included in the system PATH if the optiqor command is not recognized after installation.

Why

Fixes #None (just a documentation quick fix)

How

Added a short troubleshooting note below the go install command without modifying the existing installation workflow.

Testing

• make lint test passes locally
• go test -race ./... passes
• If a new rule: added a chart fixture in testdata/ and a golden output
• Tested locally with: Reviewed the updated README to ensure the note is correctly placed and improves the installation instructions.

Checklist

• PR title follows Conventional Commits (feat(scope): subject)
• All commits are DCO-signed (git commit -s)
• No unrelated changes pulled in
• Documentation updated where user-visible behavior changed
• No LLM calls or telemetry introduced
• No proprietary backend imports

[github-actions]

First PR — welcome aboard!

A few things to expect:

1. CI: every PR runs build + race tests + lint on Ubuntu and macOS. If something fails, the log will tell you exactly which gate.
2. DCO: every commit needs Signed-off-by:. git commit -s adds it automatically.
3. Conventional Commits: PR titles like feat(analyze): new rule or fix(cli): handle X. We squash-merge by default.
4. Review: a maintainer will review within 72 hours. Suggestions are conversations, not orders — push back if something doesn't fit your context.

If you get stuck, reply here or jump to Discussions. We want this PR to land.