Update exercises/diamond/description.md

Co-authored-by: András B Nagy <[email protected]>

Author: iHiD

exercises/diamond/description.md

@@ -43,7 +43,7 @@ These are the full requirements:
 - The first row contains one 'A'.
 - The last row contains one 'A'.
 - All rows, except the first and last, have exactly two identical letters.
-- All rows have as many trailing spaces as leading spaces. (This might be 0).
+- All rows have as many trailing spaces as leading spaces (this might be 0).
 - The diamond is horizontally symmetric.
 - The diamond is vertically symmetric.
 - The diamond has a square shape (width equals height).