Fix #8714: html: kbd role with "Caps Lock" rendered incorrectly

`:kbd:` role has to support keys in consist of multiple words (ex. caps
lock, num lock, etc.)

tests/test_markup.py

@@ -284,6 +284,13 @@ def get_verifier(verify, verify_re):
         '<p><kbd class="kbd docutils literal notranslate">-</kbd></p>',
         '\\sphinxkeyboard{\\sphinxupquote{\\sphinxhyphen{}}}',
     ),
+    (
+        # kbd role
+        'verify',
+        ':kbd:`Caps Lock`',
+        '<p><kbd class="kbd docutils literal notranslate">Caps Lock</kbd></p>',
+        '\\sphinxkeyboard{\\sphinxupquote{Caps Lock}}',
+    ),
     (
         # non-interpolation of dashes in option role
         'verify_re',