Add RFC draft for removing email validation on metada owner

Author: Mihai Tabara

rfcs/xxxx-remove-email-validation-for-metadata-owner.md

@@ -0,0 +1,34 @@
+# RFC <number> - remove the email validation for metadata.owner
+* Comments: [#<number>](https://github.com/taskcluster/taskcluster-rfcs/pull/<number>)
+* Proposed by: @mihaitabara
+
+# Summary
+
+We want to remove the email validation for `metadata.owner` to allow Github applications to safely
+set their names.
+
+## Motivation
+
+Using Github bots has become a necessity in many repositories that are already using Taskcluster as their CI. Many of these bots tweak some of the input fed in `.taskcluster.yml` without an easy way to tweak it.
+One of these examples is the `event.sender.login` which may be directly inferred from the bot without the possibility of configuring it. Since this field is often used to feed the `metadata.owner` with an email address, it
+can often break taskcluster-gitub logic.
+
+Removing the email validation causes no harm and avoids `if/else` statements that attempt to guess and re-write that field directly in the `.taskcluster.yml`, making it more suple and easy to read.
+
+# Details
+
+In the Github world, there are some helpful applications that are running in order to help developers. Examples include but are not limited to [dependabot](https://dependabot.com/) and [bors](https://github.com/bors-ng/bors-ng) which are used successful
+in projects such as [application-services](https://github.com/mozilla/application-services/) or [android-components](https://github.com/mozilla-mobile/android-components/). When `taskcluster-github` is rendering the `.taskcluster.yml`,
+it sometimes hits errors when validating the email set for `metadata.owner`. Normally that field is set to `${user}@users.noreply.github.com` where `user = ${event.sender.login}`.
+For primitive github operations, sans bots, this works well while for cron-jobs triggered from hooks, we feed that value to our covenience. However, for when we're using bots, we may not always have that flexibility of tweaking the bot's input.
+Moreover, Github itself is adding the `[bot]` string to that input, which naturally breaks any sort of email validator we have under the hood.
+
+In order to make checks such as [this](https://github.com/mozilla/application-services/blob/b4750f6c0987d76893f96ecbb2123552e6b35252/.taskcluster.yml#L43-L48) and
+[this](https://github.com/mozilla-mobile/android-components/pull/4097/files#diff-ac0229d1171c0983b27003af4c7441a5R12-R16) more generic (if we end up adding multiple bots for a repo), we propose removing the email validation for `metadata.owner`.
+
+
+To our knowledge, the `metadata.owner` holds no security concern, so removing the email validation should be harmless.
+
+# Implementation
+
+* [general bug](https://bugzilla.mozilla.org/show_bug.cgi?id=1573192)