Fix issue #15601 — Position of X-UA-Compatible, charset and viewport

Add comment to all examples

The non-responsive is correctly saying 2 instead of 3

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This way, it works in all browsers.

The validator doesn't choke anymore on this and even though it's not spec compliant, it's needed for some IE versions. So until we move favicon.ico in root, this should do the job.

Closes #13379.

- works when viewing page via file://
- sets a good example security-wise

...because we don't support it and it may cause problems for people
trying to view the docs in IE.