Tweak the copybutton settings to ignore prompts.

I still don't really know why this isn't the default.

Closes: #1246

docs/conf.py

@@ -123,19 +123,23 @@ def entire_domain(host):
 
 autosectionlabel_prefix_document = True
 
+# -- intersphinx --
+
+intersphinx_mapping = {
+    "python": ("https://docs.python.org/3", None),
+    "referencing": ("https://referencing.readthedocs.io/en/stable/", None),
+}
+
 # -- extlinks --
 
 extlinks = {
     "ujs": ("https://json-schema.org/understanding-json-schema%s", None),
 }
 extlinks_detect_hardcoded_links = True
+# -- sphinx-copybutton --
 
-# -- intersphinx --
-
-intersphinx_mapping = {
-    "python": ("https://docs.python.org/3", None),
-    "referencing": ("https://referencing.readthedocs.io/en/stable/", None),
-}
+copybutton_prompt_text = r">>> |\.\.\. |\$"
+copybutton_prompt_is_regexp = True
 
 # -- sphinxcontrib-spelling --