add note admonition

Author: mmcky

lectures/intro.md

@@ -14,6 +14,10 @@ kernelspec:
 This website presents a set of lectures on Python programming for economics and finance, designed and written by
 [Thomas J. Sargent](http://www.tomsargent.com/) and [John Stachurski](http://johnstachurski.net/). This is the first text in the series, which focuses on programming in Python.
 
+```{note}
+This site is the first of three to get update
+```
+
 For an overview of the series, see [this page](https://quantecon.org/python-lectures/)
 
 ```{tableofcontents}