feat(docs): update project documentation and enhance clarity

- Revise project overview to better reflect current goals and features of the Smart Project.
- Remove outdated sensor documentation and consolidate relevant information into a new docs/project_idea.md file.
- Ensure that the documentation aligns with the project's direction and provides a clear roadmap for contributors.

Why:
- Improve clarity and accessibility of project documentation for new contributors.
- Eliminate stale content to maintain focus on the project's objectives.

Author: Sabbir Ahmed Shourov