Add update-constraints command that allows to modify released ones

[potiuk]

This command can be used to semi-automatically update constraints in case we need to update historical version of them, because for some reason (like setuptools or pip or cython changes) we need to update individual constraints in historically released constraints.

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[amoghrajesh]

Really impressive PR! Few comments.

[potiuk]

When applying comments from @amoghrajesh I found out that the docs (especially the dev/MANUALLY...) could benefit from some consistency and similar structure for the different "manual" parts.

On one hand, it is unrelated change, on the other it's just updating the docs structure and content of a doc file tha we move and modify heavily so I went ahead and updated few more things in the same docs:

• added context explaiing what the document is about and why sometimes we need to update/refresh image cache/constraints manually

• reordered the chapters - first chapter explains how automated CI manages both image cache and constraints, then it explain how to manually refresh image cache, then how to manually refresh constraints, and eventually how to update already tagged constraints - seems it is much better and logical sequence

• also ach chapter now contains similar structure:

  • why we might want to do it?
  • how to do it?
  • are there any dangers involved?

[potiuk]

:D looking for some more reviews :)

[amoghrajesh]

Looks really good now!
Few nits which you can choose to ignore, @potiuk

[potiuk]

Applied second round of comments.

[amoghrajesh]

Looks good, one small nit. Feel free to ignore

[potiuk]

Breeze PR looks for approval :)

[vijayasarathib]

LGTM

[potiuk]

I appreciate the updates to the documentation structure and content. Could you confirm that the documentation is complete and aligns with the implemented functionality?

Please check it before you ask such questions. It will be TERRIBLY, TERRIBLY annoying if you keep on asking those questions @vijayasarathib before checking it first.

Please STOP before you go any further.