Docs improvements for build from scratch

[Anish9901]

HackMd notes

Checklist

• My pull request has a descriptive title (not a vague title like Update index.md).
• My pull request targets the develop branch of the repository
• My commit messages follow best practices.
• My code follows the established code style of the repository.
• I added tests for the changes I made (if applicable).
• I added or updated documentation (if applicable).
• I tried running the project locally and verified that there are no
  visible errors.

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(b) The contribution is based upon previous work that, to the best
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(c) The contribution was provided directly to me by some other
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[mathemancer]

LGTM

[pavish]

Looks good to me!