Move redundant installation content into shared folder

[Reshrahim]

Thank you for helping make the Radius documentation better!

Please follow this checklist before submitting:

• Read the contribution guide
• Commands include options for Linux, MacOS, and Windows within codetabs
• New file and folder names are globally unique
• Page references use shortcodes instead of markdown or URL links
• Images use HTML style and have alternative text
• Places where multiple code/command options are given have codetabs

In addition, please fill out the following to help reviewers understand this pull request:

Description

This PR moves redundant installation content into a shared folder and reads from it wherever needed. Helps with easier maintenance to keep up with changes.

Auto-generated description

🤖 Generated by Copilot at d20ac36

Summary

🗂️📝🔄

This pull request refactors the installation instructions for the rad CLI, the VS Code extension, and the Radius control-plane by using a new read shortcode that reads the content from shared files in the shared-content directory. This improves the maintainability and consistency of the documentation.

read shortcode added
content from shared files used
autumn of repeats

Walkthrough

• Add a new shortcode read that reads and renders the content of a file as markdown (link)
• Add three shared files that contain the installation instructions for the rad CLI, the VS Code extension, and the Radius control-plane (link, link, link)
• Replace the inline installation instructions with the read shortcode in the following pages: getting-started/index.md, guides/operations/kubernetes/kubernetes-upgrade/index.md, guides/tooling/rad-cli/howto-rad-cli/index.md, guides/tooling/vscode/howto-vscode-bicep/index.md, and installation/index.md (link, link, link, link, link)
• Add a new mount point for the module in the config.toml file to access the shared-content directory (link)

Issue reference

[github-actions]

Azure Static Web Apps: Your stage site is ready! Visit it here: https://wonderful-plant-020417a1e-798.westus2.azurestaticapps.net
Password: Radiu$1234

[github-actions]

Azure Static Web Apps: Your stage site is ready! Visit it here: https://wonderful-plant-020417a1e-798.westus2.azurestaticapps.net
Password: Radiu$1234

[AaronCrawfis]

Love this! One note on shortcode usage