bug #11450 [Docs] Enable redirections on ReadTheDocs (pamil)
bug #11450 [Docs] Enable redirections on ReadTheDocs (pamil)

This PR was merged into the 1.6 branch.

Discussion
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The redirections map defined in `docs/redirection_map` works correctly for local builds but is skipped for docs hosted on ReadTheDocs because they use `readthedocs` builder instead of `html` one.

<img width="794" alt="CleanShot 2020-05-11 at 13 16 36@2x" src="https://user-images.githubusercontent.com/1897953/81555991-d9acbb00-9389-11ea-81d6-eb23b8209542.png">

This PR should fix that (I hope so). Aiming at 1.6 because it's the earliest branch in which we wanted to create redirections.

Commits
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98acadad2a8bd70e08e7f907f8c600af97074683 [Docs] Enable redirections on ReadTheDocs

Zales0123/Sylius,kayue/Sylius,lchrusciel/Sylius,GSadee/Sylius,SyliusBot/Sylius,lchrusciel/Sylius,diimpp/Sylius,pjedrzejewski/Sylius,Zales0123/Sylius,Arminek/Sylius,pjedrzejewski/Sylius,Sylius/Sylius,GSadee/Sylius,Arminek/Sylius,diimpp/Sylius,pamil/Sylius,antonioperic/Sylius,mbabker/Sylius,Sylius/Sylius,101medialab/Sylius,lchrusciel/Sylius,Sylius/Sylius,GSadee/Sylius,antonioperic/Sylius,Arminek/Sylius,mbabker/Sylius,SyliusBot/Sylius,pamil/Sylius,loic425/Sylius,Zales0123/Sylius,mbabker/Sylius,pjedrzejewski/Sylius,101medialab/Sylius,kayue/Sylius,mbabker/Sylius,loic425/Sylius,pjedrzejewski/Sylius,pamil/Sylius,diimpp/Sylius,SyliusBot/Sylius,loic425/Sylius,101medialab/Sylius,antonioperic/Sylius,kayue/Sylius