docs: add take_std(in|out|err) & random sort

[AnirudhG07]

Referring to issue #73, the Command:std(in|out|err) was already present in the docs.
So i added the take_std(in|out|err) under the Child sub, in utils.md

If I have misunderstood any part of it, pls do correct!
Thanks!

[AnirudhG07]

Also added write_all and flush in the child. I hope they are fine...
(Why is merge showing errors?)

[AnirudhG07]

Please check #103 before this. the commits here are present in that PR too(mistakenly)

[sxyazi]

Could you add some examples for them please?

[AnirudhG07]

uh... ill try, it took a while for me to understand that small rust code for it(I m not familiar with rust). I'll update if I am unable too.
Rest of the things are correct??

[AnirudhG07]

I added random sort in keymaps as mentioned in #70 . Is there another place it needs to be added @sxyazi ?

[AnirudhG07]

Is it possible to merge this branch soon @sxyazi so that I can add some UI components to the docs, as i told before. otherwise the new branch will be built on top of this main and i ll face some issues dealing with commits and all.

[sxyazi]

Thanks!