[information-architecture] Conflicting Go prerequisite guidance across development entry points

## Information Architecture Findings

### 1. Conflicting prerequisite guidance in parallel onboarding entry points
**Area:** Consistency
**Component(s):** `docs/developing.md`, `DEVELOPING.md`
**Problem:** Two primary “how to develop” entry points present contradictory prerequisite requirements for the same setup flow. In `docs/developing.md`, Go is documented as required (`docs/developing.md:15`), while `DEVELOPING.md` states Go is optional and only needed for non-release compiler builds (`DEVELOPING.md:15`). Users following docs-site onboarding versus repository onboarding can reach different conclusions about required tooling, causing confusion and unnecessary setup work.
**Suggested improvement:** Align both pages to one authoritative prerequisite model (preferably the current “Go optional” guidance), and cross-link a single source-of-truth prerequisites section so both entry points stay consistent.

## Suggested Actions
- [ ] Update `docs/developing.md` prerequisite text to match `DEVELOPING.md` (or vice versa, if policy changed).
- [ ] Add a short “source of truth” reference between the two pages to prevent future drift.
- [ ] Confirm quick-start instructions in both files remain consistent after prerequisite update.

---
[What is this?](https://ela.st/github-ai-tools) | [From workflow: Trigger Information Architecture](https://github.com/elastic/ai-github-actions/actions/runs/32755290538)

Give us feedback! React with 🚀 if perfect, 👍 if helpful, 👎 if not.