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* Added trizen to the archlinux plugin

trizen is the recomended solution for using the Arch User Repository.
both yaourt and pacaur have some issues.

Signed-off by: Arthur Brainville (Ybalrid) <ybalrid@ybalrid.info>

* Add trizen aliases to the readme

Also fixed inconsistency in formatting on readme file.
(also added myself in the contributor list)

This commit removes most of its contents: it just leaves the
contribution signature. The rest is obsolete and superseeded
by #5460, but the contribution is still valuable.

Related: #4263.
Signed-off-by: Marc Cornellà <marc.cornella@live.com>

Signed-off-by: Marc Cornellà <marc.cornella@live.com>