docs: rearranged cli/runtime related sections

[cyfung1031]

What does this PR do?

• Documentation or TypeScript types (it's okay to leave the rest blank in this case)
• Code changes

How did you verify your code works?

N/A

Reason and Changes

Added Scaffolding section (docs/scaffolding/)

• The project creation (folder scaffolding) should not put inside intro, it should be a new section before cli bun run
• Intro shall focus on the overall first time usage, like how to install and Quickstart.
• bun init and bun create shall be separated into two different sub pages, as users shall use either bun init or bun create to scaffold a new project. (docs/scaffolding/bun-create.md and docs/scaffolding/bun-init.md)
• typescript settings shall be part of the scaffolding, not intro. (docs/scaffolding/typescript.md)

Extracted bun add --global into separate sub page. (docs/install/global-install.md)

• bun add --global is not to adding package to the local project folder.
• As it does not modify any file (e.g. package.json) inside the local project folder, it should be extracted as a new sub page.

Relocated or Removed obsoleted files docs/typescript.md, docs/cli/bun-init.md, and docs/templates.md

Added Information in installation.md for the manual global installation setup in macOS / Linux (bash).

Updated nav.ts accordingly

Updated README.md for the revised docs path.

Added bun --version and bun --revision in installation.md for users to check the installation.