Update docs to reflect the drop of active support of Internet Explorer 11

Problem to solve

The current documentation states the dropping of support of IE11 as a future occurence.

We should update the docs in 13.0 top reflect the dropped support of IE11 as of the current release.

As per the plan in: #197987 (closed) and #55313 (closed)

Further details

A deprecation message has been added in %12.9 with: gitlab-com/www-gitlab-com!43831 (merged)

Proposal

Update doc/install/requirements.md to use the past tense in the section of Supported web browsers.

changed milestone to %13.0

added Technical Writing browser:ie11 documentation labels

@leipert Can you please confirm we didn't have an issue for this update?

Want to take care of this for %13.0 or should I find someone in groupsource code for this?

Thanks in advance!

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changed due date to May 25, 2020

changed due date to May 14, 2020

@andr3 Sounds good to me. Will change it around May 14th, so that it makes into 13.0.

assigned to @leipert

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changed milestone to %13.1

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mentioned in issue #219498 (closed)

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mentioned in merge request !40952 (merged)

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Verified in production

closed

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