Fix image syntax in README.md

Author: codingjoe

README.md

@@ -24,7 +24,7 @@ Django Mail Auth features:
 - drop in Wagtail login replacement
 - extendable SMS support
 
-![](sample.png){alt="screenshot from a login form" width="425px"}
+<img src="sample.png" alt="screenshot from a login form" width="425px">
 
 This project was inspired by: