[Docs]: toHaveClass should have a proper "relaxed regex" example

[rrauenza]

Page(s)

https://playwright.dev/docs/api/class-locatorassertions#locator-assertions-to-have-class

Description

The docs mention a 'relaxed regular expression' but doesn't define what 'relaxed' means. The existing example of toHaveClass(/selected/) would also match class="selectedfoo row"

I think it could be helpful if the example used the zero length word boundary pattern, \b:

<div class='selected row' id='component></div>

const locator = page.locator('#component');
await expect(locator).toHaveClass(/\bselected\b/);
await expect(locator).toHaveClass(/\brow\b/);

Unfortunately, \b considers - to be a boundary, so there is still some possible ambiguity. Perhaps /(^|\s)selected(\s|$)/ would be better

<div class='selected row' id='component></div>

const locator = page.locator('#component');
await expect(locator).toHaveClass(/(^|\s)selected(\s|$)/);
await expect(locator).toHaveClass(/(^|\s)row(\s|$)/);

\s could be replaced with (space), but it may be clearer to have the \s