a11y: search button is inaccessible

[CBID2]

Description

I conducted an accessibility test on the site and one of the results revealed that the search button is empty or has no value text(see below screenshot for more context), which makes it difficult for screen reader users to understand the search button's function.

Screenshot

Proposed Solution

I will add some text within the element to make it more descriptive.

Additional Information

I would like to count this contribution for Aperte 2.0