address a comment

Co-authored-by: Niels Dossche <7771979+nielsdos@users.noreply.github.com>

Author: SakiTakamachi

reference/bc/functions/bcround.xml

@@ -41,7 +41,7 @@
  <refsect1 role="returnvalues">
   &reftitle.returnvalues;
   <simpara>
-   Returns a BCMath string number representing <parameter>num</parameter> rounded to the given precision.
+   Returns a numeric string representing <parameter>num</parameter> rounded to the given precision.
   </simpara>
  </refsect1>