CI: add admonition to every JupyterLite kernel

Author: agriyakhetarpal

doc/source/conf.py

@@ -293,3 +293,13 @@
 
 global_enable_try_examples = True
 try_examples_global_button_text = "Try it in your browser!"
+try_examples_global_warning_text = (
+    """These interactive examples with JupyterLite are experimental and
+    may not always work as expected. The execution of cells containing import
+    statements will result in high bandwidth usage and may take a long time to
+    complete.
+
+    If you are on the latest version of the documentation, please install the
+    latest version of PyWavelets to ensure the examples work as expected, via
+    the following command:"""
+)