Fix typos in core README files

+++ b/core/tests/README.md
@@ -18,7 +18,7 @@ Note: functional tests have to be invoked with a user in the same group as the
diff --git a/sites/example.sites.php b/sites/example.sites.php

Why this file is deleted?

Work in progress.

Hi people.

Thanks for your contribution @sandeepscs.

I create a fix with a patch with example.sites.php file included.

Patch it's in attachment.

Good Work and Good Week.

Regards.

Hello,

Thanks for correct this !

Thanks for your review @rodrigoac.

Hugs.

+++ b/core/tests/README.md
@@ -18,7 +18,7 @@ Note: functional tests have to be invoked with a user in the same group as the
-To develop locally, a straigtforward - but also less secure - approach is to run
+To develop locally, a straightforward - but also less secure - approach is to run

This line exceeds 80 columns.

N/A

It's true. Good catch.

Thank you very much for your review @cilefen.

New patch it's in attachment.

Good Work and Good Week.

Regards.

Tested and it works this time. Submitted a review screenshot

Good Work..
Patch is working.

Hi! Good Morning.

Thank you very much for yours reviews guys.

Good Work.

Hugs.

Thank you for reviewing this issue!

The automated testing infrastructure tells us whether the patch applies, so we do not need people to review that. It is also not sufficient criteria for the issue to be marked "Reviewed and Tested by the Community".

What we do need people to review is whether the issue has a correct scope, whether it passes the core gates, whether the solution completely fixes the problem without introducing other problems, and whether it's the best solution we can come up with. See the patch review guide for more information.

When you do post a review, be sure to describe what you reviewed and how. This helps other reviewers understand why you considered the issue RTBC (and is considered for issue credit).

@renatog patch mentioned in #12 is working. It fixes the spelling mistake.

Patch in #12 works as designed. Scope is alright and core gates are passed. This is the best solution.

Dear everyone who reviewed this issue:

Screenshots of code are never part of a review. Screenshots of UI changes caused by code changes are sometimes appropriate, and sometimes asked for. I checked every README file, because that is a better scope for this issue. I did it this way:

find core/ -name README.* -exec aspell -c {} \;

In fact, this one is the only mistype I could find, and this is appropriately scoped now.

Committed 4a892d8 and pushed to 8.4.x. Cherry-picked as d1de3df and pushed to 8.3.x. Thanks!