Docs: add missing build job build and install to build customization page

[agjohnson]

This page does not mention the new build jobs:

• https://docs.readthedocs.io/en/stable/build-customization.html

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• Describe build.jobs.build.html and friends
• Describe build.jobs.install
• Update uv instructions to use build.jobs.install
• Add examples for new jobs

[humitos]

We have a few related issues from where we can take some examples / use cases:

• Npm install support #11216
• Add Pixi Build Support #11548
• build.commands shall support custom package installation (build.apt_packages) #9599
• Docs: configuration guide content on new tools #10418
• Build: build.jobs could have pre_upload and post_upload jobs #9139
• Support uv #11289