Fix the demo's LateX.

Elementary, my dear Einstein.

README.md

@@ -12,9 +12,9 @@ A flat-file database of courses in multiple languages.
 
 You can use LateX in the courses :
 
-    $`E=m\cdotc^2`$
+    $`E = m \cdot c^2`$
 
-yields $`E=m\cdotc^2`$
+yields $`E = m \cdot c^2`$
 
 > You can omit the _backticks_ (`) but the preview in gitlab won't work.