chore: Remove Docs from OSx Repo

Description

This PR has the complete removal of OSx hand-written documentation from OSx. With its necessary changes in the workflows.

It also adds a checkbox in the PR template so from now on, anyone who makes important changes in the OSx repo should create a follow-up task to reflect those changes in the Developer Portal.

At the end, there are some orthographic corrections in the Lifecycle .md files.

Please take a close look into the GitHub files, and see at the end if the orthographic corrections are correct.

Task ID: OS-1352

Type of change

[x] Bug fix (non-breaking change which fixes an issue)

Checklist:

[x] I have selected the correct base branch.
[x] I have performed a self-review of my own code.
[ ] I have commented my code, particularly in hard-to-understand areas.
[ ] My changes generate no new warnings.
[ ] Any dependent changes have been merged and published in downstream modules.
[ ] I ran all tests with success and extended them if necessary.
[ ] I have updated the CHANGELOG.md file in the root folder.
[ ] I have updated the DEPLOYMENT_CHECKLIST file in the root folder.
[ ] I have updated the UPDATE_CHECKLIST file in the root folder.
[ ] I have updated the Subgraph and added a QA URL to the description of this PR.

aragon / osx