Restructure and Enhance the QuickStart documentation

[heyselbi]

The new documentation should have sections that answer the following questions:

• Installation Steps
• How do you add/deploy a model and a sample inference URL with a sample model in the example?
• Remove a model (undeploy)
• Canary rollout, A/B testing
• How to upgrade runtime?
• How to access metrics?

[heyselbi]

Draft PR: #61

[heyselbi]

Melissa's PR: https://github.com/opendatahub-io/caikit-tgis-serving/pull/65/files

[bdattoma]

Some feedbacks from QE:

1. In the README.md there are links which bring to blank page with "TO DO" text. The 2 links are:

• https://github.com/opendatahub-io/caikit-tgis-serving/blob/main/demo/kserve/traffic-splitting.md
• https://github.com/opendatahub-io/caikit-tgis-serving/blob/main/demo/kserve/upgrade-runtime.md

What's the plan? Shall we leave these blank for the 5 Sept release? @heyselbi @MelissaFlinn

2. the script based installation guide should mention to set the BREW_TAG variable before running the script, if the "brew" operator type is chosen. cc: @Jooho

3. in the Procedure section of README.md, it mentions Open Data Hub among the requirements, but it is not a requirement cc: @Jooho

[heyselbi]

Closing the issue as the main restructuring is complete. Adding two follow up issues:

1. For two remaining sections: Update runtime and Traffic splitting (issue)
2. Metrics docs need some clarification on how to obtain certain metrics (issue)