Add initial OTel distribution specification

[stevejgordon]

Adds a new markdown file to define a specification for Elastic OpenTelemetry distributions. This includes two initial specification items up for discussion.

• [x] Create PR as draft
• [ ] Approval by at least one other agent
• [ ] Mark as Ready for Review (automatically requests reviews from all agents and PM via CODEOWNERS)
  • Remove PM from reviewers if impact on product is negligible
  • Remove agents from reviewers if the change is not relevant for them
• [ ] Approved by at least 2 agents + PM (if relevant)
• [ ] Merge after 7 days passed without objections \ To auto-merge the PR, add /schedule YYYY-MM-DD to the PR description. ~- [ ] Create implementation issues through the meta issue template (this will automate issue creation for individual agents)~

[stevejgordon]

Closing as we will relocate this.