formating molecules.cells exercise

subjects/molecules-cells.en.md

@@ -3,13 +3,16 @@
 ### Instructions
 
 Write two functions:
-  - `RNA` that given a DNA strand it must return is complement RNA
-  - `DNA` that given a RNA strand it must return is complement DNA (invert RNA)
+
+- `RNA` that given a DNA strand it must return is complement RNA
+- `DNA` that given a RNA strand it must return is complement DNA (invert RNA)
 
 Since both strands are a sequence of nucleotides. It will be given the four nucleotides and its complements
 
+```
 DNA | RNA
  G  -  C
  C  -  G
  T  -  A
- A  -  U
+ A  -  U
+```