Address 0.25.0 release PR comments

[LinasKo]

Description

This PR addresses comments on the release PR.

1. Improve Discord Icon in README
2. Using KeyPoints.as_detections() for conversion before keypoint tracking
3. Removed LineZone property dosctrings, added to 'Attribute' section in class LineZone docstring. This is consistent with PolygonZone.
4. Split How To guide for KeyPoints into multiple sections
5. Added metrics plots
6. Added metrics print results

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

How has this change been tested, please provide a testcase or example of how you tested the change?

1. Looked at + clicked discord icon in the README: https://github.com/roboflow/supervision/tree/fix/address-release-pr-comments

• The change includes whitespace changes to the README, but I cannot spot any regressions.

2. Built docs, checked utils, keypoints, How-To-Track sections. Colab: https://colab.research.google.com/drive/10PMuW0IyaksofqI70NLnB_-Fnr4oKVmk?usp=sharing
3. Checked docs for LineZone attributes.
4. See http://127.0.0.1:8000/how_to/track_objects/#keypoints
5. see metrics docs, check for charts
6. see metrics docs, check for print results

Any specific deployment considerations

For example, documentation changes, usability, usage/costs, secrets, etc.

Docs

• Docs updated? What were the changes: