add button fig

basic_concepts/index.html

@@ -95,6 +95,8 @@ A good starting point for newcomers in the electronics field looking for what is
 
   ### [Resistors and switches](https://roberthart56.github.io/SCFAB/SC_lab/Sensors/Button/index.html)
 
+    ![button circuits](../images/buttong_config.png)
+
   ### Circuit Analysis
 
       - Goal: volatge and current prediction within a purely resistive powered by a direct current (dc) source such as a battery