docs: Add service READMEs and update homelab overview documentation

This commit introduces dedicated `readme.md` files for individual services
within both the `Local Homelab` and `Oracle Homelab` directories.

Each service-specific README provides a brief description of the service,
its deployment method (Docker Compose), and references relevant
configuration files.

Additionally, the main `Local Homelab/readme.md` was updated to
enumerate all deployed services, describe the repository's structure,
and include pertinent links.

This change aims to significantly improve the clarity, organization,
and discoverability of information across the homelab setups.

Local Homelab/homeassistant/readme.md

@@ -0,0 +1,13 @@
+# Home Assistant
+
+[Home Assistant](https://www.home-assistant.io/) is an open-source home automation platform that puts local control and privacy first.
+
+## 🚀 Deployment
+
+This service is deployed using Docker Compose.
+
+### Files
+- `docker-compose.yml`: Docker Compose configuration.
+
+## 🔗 Links
+- [Local Homelab](../)