chore(about page): fix punctuation (@Leonabcd123) (monkeytypegame#6911)

### Description

Changed punctuation in the about page. We can also make the text in the
parenthesis a standalone sentence by just removing the parenthesis.

Author: Leonabcd123

frontend/src/html/pages/about.html

@@ -142,11 +142,11 @@ <h2>
     </div>
     <p>
       After completing a test you will be able to see your wpm, raw wpm,
-      accuracy, character stats, test length, leaderboards info and test info.
+      accuracy, character stats, test length, leaderboards info and test info
       (you can hover over some values to get floating point numbers). You can
       also see a graph of your wpm and raw over the duration of the test.
       Remember that the wpm line is a global average, while the raw wpm line is
-      a local, momentary value. (meaning if you stop, the value is 0)
+      a local, momentary value (meaning if you stop, the value is 0).
     </p>
   </div>
   <div class="section">