HTML errors and warnings

[stweil]

Describe the bug The INCEpTION web pages include HTML 5 code with errors and warnings:

Error: Stray end tag meta.
Error: An img element must have an alt attribute, except under certain conditions. For details, consult [guidance on providing text alternatives for images](https://www.w3.org/WAI/tutorials/images/).
Warning: Consider adding a lang attribute to the html start tag to declare the language of this document.
Warning: The type attribute is unnecessary for JavaScript resources.

Wrong HTML code typically works differently on different web browser, so can be the reason why certain web browsers don't work..

To Reproduce I installed the latest Docker image (INCEpTION -- 24.1 (2022-08-23 13:26:20, build 631d180b)). Use the W3C validator to validate selected pages either by URI (normally only possible for login page) or by direct input (possible for any page).

Expected behavior Ideally all web pages should pass without any HTML error or warning.

[stweil]

More reports for the first page after successful login:

Error: Element [span](https://html.spec.whatwg.org/multipage/#the-span-element) is missing one or more of the following attributes: role.
Error: Element [div](https://html.spec.whatwg.org/multipage/#the-div-element) not allowed as child of element [span](https://html.spec.whatwg.org/multipage/#the-span-element) in this context. (Suppressing further errors from this subtree.)
Error: No p element in scope but a p end tag seen.
Error: Element [p](https://html.spec.whatwg.org/multipage/#the-p-element) not allowed as child of element [small](https://html.spec.whatwg.org/multipage/#the-small-element) in this context. (Suppressing further errors from this subtree.)

[stweil]

There remain unsolved HTML errors even after the latest commits. Therefore I suggest to keep this issue open.

[reckart]

I'll keep it open for further PRs on v25 but will close it when v25 gets released. A new issue can be opened for issues that remain after v25.