Add partner agents (#405)

* Add partner agents: Elastic, New Relic, MongoDB, Neo4j, Monday.com, and Apify

* Fix agent file naming to match conventions

* Add new partner agents and update Partners collection metadata

- Add six new partner agents to the Partners collection:
  - Apify Integration Expert
  - Elasticsearch Agent
  - Monday Bug Context Fixer
  - MongoDB Performance Advisor
  - Neo4j Docker Client Generator
  - New Relic Deployment Observability Agent
- Update partners.collection.yml to include new agent definitions
- Update Partners collection item count from 11 to 17 in:
  - README.md
  - collections/partners.md footer
  - docs/README.collections.md
  - docs/README.agents.md

* Fix New Relic agent filename and update partner references

- Remove obsolete New Relic Deployment Observability agent definition file
  (newrelic-deployment-observability-agent.md)
- Update partners collection to reference the correct agent filename:
  newrelic-deployment-observability.agent.md
- Keep partners.collection.yml items list in proper alphabetical order
- Update New Relic agent links in:
  - collections/partners.md
  - docs/README.agents.md

* Update agents/elasticsearch-observability.agent.md

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update generated README files

---------

Co-authored-by: Alexis Abril <alexisabril@github.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

README.md

@@ -24,7 +24,7 @@ Discover our curated collections of prompts, instructions, and chat modes organi
 | Name | Description | Items | Tags |
 | ---- | ----------- | ----- | ---- |
 | [Awesome Copilot](collections/awesome-copilot.md) | Meta prompts that help you discover and generate curated GitHub Copilot chat modes, collections, instructions, prompts, and agents. | 6 items | github-copilot, discovery, meta, prompt-engineering, agents |
-| [Partners](collections/partners.md) | Custom agents that have been created by GitHub partners | 11 items | devops, security, database, cloud, infrastructure, observability, feature-flags, cicd, migration, performance |
+| [Partners](collections/partners.md) | Custom agents that have been created by GitHub partners | 17 items | devops, security, database, cloud, infrastructure, observability, feature-flags, cicd, migration, performance |
 
 
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