[Docs] Fix typos, improve, update at Conceptual Guides page (huggingface#5585)

* Fix typos, improve, update

* Update docs/source/en/conceptual/contribution.md

Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>

* Update docs/source/en/conceptual/contribution.md

Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>

* Update docs/source/en/conceptual/philosophy.md

Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>

* Update philosophy.md

* Update philosophy.md

* Update docs/source/en/conceptual/philosophy.md

Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>

* Update docs/source/en/using-diffusers/controlling_generation.md

Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>

* Update docs/source/en/using-diffusers/controlling_generation.md

Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>

* Remove e.g.; some Grammarly fixes

* Update docs/source/en/conceptual/philosophy.md

Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>

* Update contribution.md

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Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>

Author: tolgacangoz