Update check-packages.py

with open(os.path.join(doc_dir, 'Packages_standard.rst')) as fp:

    text = fp.read()

matches = re.findall(':ref:`([A-Z0-9-]+) <[A-Z0-9-]+>`', text, re.MULTILINE)

matches = set(re.findall(':ref:`([A-Z0-9-]+) <[A-Z0-9-]+>`', text, re.MULTILINE))

for p in stdpkg:

  if not p in matches:

    counter += 1

with open(os.path.join(doc_dir, 'Packages_user.rst')) as fp:

    text = fp.read()

matches = re.findall(':ref:`([A-Z0-9-]+) <[A-Z0-9-]+>`', text, re.MULTILINE)

matches = set(re.findall(':ref:`([A-Z0-9-]+) <[A-Z0-9-]+>`', text, re.MULTILINE))

for p in usrpkg:

  if not p in matches:

    counter += 1

with open(os.path.join(doc_dir, 'Packages_details.rst')) as fp:

    text = fp.read()

matches = re.findall(':ref:`([A-Z0-9]+) <PKG-\\1>`', text, re.MULTILINE)

matches = set(re.findall(':ref:`([A-Z0-9]+) <PKG-\\1>`', text, re.MULTILINE))

for p in stdpkg:

    if not p in matches:

        counter += 1

        print(f"Standard package {p} missing in Packages_details.rst")

matches = re.findall(':ref:`(USER-[A-Z0-9]+) <PKG-\\1>`', text, re.MULTILINE)

matches = set(re.findall(':ref:`(USER-[A-Z0-9]+) <PKG-\\1>`', text, re.MULTILINE))

for p in usrpkg:

    if not p in matches:

        counter +=1