Revived Aliases page, wrote about roboflow ecosystem, fixed minor issues

[LinasKo]

Description

Pages on the left now have a basic section.

The goal is to answer questions:

• What is inference in the context of Roboflow (+ what other tools are available)
• What kind of models can I run?
• How can I get model_ids?
• I have weights already - what do I do?

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)
• [x] This change requires a documentation update

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

mkdocs serve

Any specific deployment considerations

1. Docs need to be deployed.
2. It assumes the aliases for keypoint detection are available.

Docs

• [x] Docs updated.