Replace `tabindex` example in submit button function docs

[sabernhardt]

[21311] removed positive tabindex values from the submit_button() and get_submit_button() functions, but tabindex="1" is still the example for $other_attributes in their documentation.

[sabernhardt]

Core uses id, disabled, aria-describedby and/or data-wp-lists for some of its submit buttons. Or there might be a better option.

Updates the docs on submit_button and get_submit_button function to match the general implementation used in wordpress. In ticket https://core.trac.wordpress.org/changeset/21311 the usage of tabindex="1" was removed and it was suggested that another example be used. This PR switches the docs to use the id attribute as an example instead.

Trac ticket: [](https://core.trac.wordpress.org/ticket/59768)

[benjaminknox]

In ​https://github.com/WordPress/wordpress-develop/pull/5605 I chose to use the id attribute as an example, I think it is a pretty good example for the button considering it would be set by developers pretty often.

[sabernhardt]

The ID should be a good choice. I have a small concern that a developer might use exactly the same ID in a plugin, but Core's search-submit example is probably better than imagining a hypothetical example.

[SergeyBiryukov]

In 57114:

Docs: Replace tabindex example in submit button functions documentation.

Most of the tabindex attributes across the admin were removed in [21311].

This commit updates the example for the $other_attributes parameter to use the id attribute instead.

Includes synchronizing documentation between submit_button() and get_submit_button().

Follow-up to [15810], [16061], [21311], [27136], [31599].

Props benjaminknox, sabernhardt, fushar, SergeyBiryukov.
Fixes #59768.

Thanks for the PR! Merged in r57114.