updating documentation for ticket #11443

[devkthines]

Description

I updated the instructions and included build instructions in the quickstart, i included the build in the build the code section before start. It was crucial so the build is ran first.

The change solves several potential problems:

Prevents Server Crashes: By ensuring that the npm run build command is run, all necessary files are generated before starting the server, preventing crashes or errors related to missing files.

Ensures Correct Asset Processing: It guarantees that all assets, such as GLSL shaders, are properly processed and available in their required formats, avoiding runtime issues and improving the reliability of the development server.

Provides a Clear Development Workflow: Adding the build step to the "Quickstart" section creates a clear and repeatable development process. This helps new developers or contributors quickly get up to speed and reduces confusion about the necessary setup steps.

Improves Documentation: Including the build step in the documentation ensures that it aligns with the actual development workflow and best practices. This helps avoid discrepancies between the documented process and the required steps to successfully run the project.

Issue number and link

##11443

Testing plan

Author checklist

• [ X] I have submitted a Contributor License Agreement
• [x ] I have added my name to CONTRIBUTORS.md
• [ ] I have updated CHANGES.md with a short summary of my change
• [ ] I have added or updated unit tests to ensure consistent code coverage
• [x ] I have updated the inline documentation, and included code examples where relevant
• [ x] I have performed a self-review of my code

[github-actions[bot]]

Thank you for the pull request, @devkthines! Welcome to the Cesium community!

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[ggetz]

Thanks @devkthines! These changes look good. Once you bring over changes from https://github.com/CesiumGS/cesium/pull/12154, this should be good to merge.

[devkthines]

Just closed #12154 and added that to this pull request. ready to merge!

[ggetz]

Thanks @devkthines! After running CI, the linting checked failed. It looks like there is some minor markdown cleanup needed:

Documentation/Contributors/BuildGuide/README.md:22 MD031/blanks-around-fences Fenced code blocks should be surrounded by blank lines [Context: "```"]
Documentation/Contributors/BuildGuide/README.md:27 MD031/blanks-around-fences Fenced code blocks should be surrounded by blank lines [Context: "```"]
Documentation/Contributors/BuildGuide/README.md:72 MD031/blanks-around-fences Fenced code blocks should be surrounded by blank lines [Context: "```"]

[devkthines]

Updated, looks like it passed all tests. Thank you!

[ggetz]

Thanks @devkthines!