Misleading documentation on rST hyperlink syntax.

Describe the bug

The reStructuredText Primer (doc/usage/restructuredtext/basics.rst) starts the section on External links with

Use ```Link text <https://domain.invalid/>`_`` for inline web links. 

which is, according to the reStructuredText Markup Specification the syntax for a "named hyperlink reference with embedded URI", the most complex and most misunderstood link syntax variant.

Users thus primed will be surprised when a subsequent "inline link" with the same link text results in a WARNING Duplicate explicit target name: "link text" because the syntax is equivalent to the link–target pair ("reference link")

Use ```Link text`_`` for hyperlinks. Add a target block::

    .. _link text: https://domain.invalid/

at a suitable place.

and generates two Doctree elements:

<reference name="Link text" refuri="https://domain.invalid/">Link text</reference>
<target ids="link-text" names="link\ text" refuri="https://domain.invalid/"></target>

The rST analogon to Markup "inline links" is an "anonymous hyperlink reference with embedded URI/alias" which uses a double trailing underline.

There is actually no good reason to use a named link with embedded href
(with single trailing underline):

• If the established reference name is used at several places, a separate named target adds clarity.

• One-off use cases are better served with the anonymous variant (with double trailing underline) or an "normal" anonymous reference – target pair.

Suggestion:

• Start the "primer" documentation section with "reference links". In rST, they are easier than "inline links".
• For "inline links", write

  Use ```Link text <https://domain.invalid/>`__`` for inline web links 
  (**mind the double underline at the end**, for details see the `rST specification`__).
  
  __ https://docutils.sourceforge.io/docs/ref/rst/restructuredtext.html#embedded-uris-and-aliases`__
  

How to Reproduce

index.rst:

The references `link text <https://domain.invalid/>`_
and `link text <https://example.com/>`_ generate a warning.

Environment Information

The bug is in the current online documentation
https://www.sphinx-doc.org/en/master/usage/restructuredtext/basics.html#external-links

Read doc/usage/restructuredtext/basics.rst and reproduce the duplicate-target warning with the issue's index.rst example. Update the External links section to distinguish reference links from anonymous embedded-URI links, then verify the documentation no longer recommends the misleading single-underline syntax.