address a comment

Co-authored-by: Gina Peter Banyard <[email protected]>

Author: SakiTakamachi

reference/bc/bcmath.number.xml

@@ -72,9 +72,9 @@
     <varlistentry xml:id="bcmath-number.props.value">
      <term><varname>value</varname></term>
      <listitem>
-      <para>
+      <simpara>
        A string representation of an arbitrary precision number.
-      </para>
+      </simpara>
      </listitem>
     </varlistentry>
     <varlistentry xml:id="bcmath-number.props.scale">