Update JavaScript API Reference for v5

[colinrotherham]

This PR simplifies the "JavaScript API Reference" introduction by:

1. Clearly linking to the new "Configure components" page
2. Matching config wording to "Configure components" headings
3. Adding anchor links to each component by name
4. Removing the Button example

Regarding 4) we have better CharacterCount examples on "Configure components" already

Configuration objects or options

I've also clarified a few mix-ups between "configuration" and "options" such as:

- Read the JavaScript API Reference for the configuration accepted by each component.
+ Read the JavaScript API Reference for the list of options in each component configuration.

- Read the JavaScript API Reference for the configuration accepted by `initAll`.
+ Read the JavaScript API Reference for the list of components in the `initAll` configuration.

[netlify[bot]]

✅ Deploy Preview for govuk-frontend-docs-preview ready!

Name	Link
🔨 Latest commit	99ded26be6c7643ed73e581c0236d7ce1ff6484d
🔍 Latest deploy log	https://app.netlify.com/sites/govuk-frontend-docs-preview/deploys/65731dee41d5ac0008ef6500
😎 Deploy Preview	https://deploy-preview-402--govuk-frontend-docs-preview.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.