make used terms more uniform (dotnet#8130)

Author: zp-zpanda

xml/System.Numerics/BitOperations.xml

@@ -84,7 +84,7 @@
       </Parameters>
       <Docs>
         <param name="value">The value to evaluate as being a power of two.</param>
-        <summary>Evaluates whether the specified <see cref="T:System.Int64" /> value is a power of 2.</summary>
+        <summary>Evaluates whether the specified <see cref="T:System.Int64" /> value is a power of two.</summary>
         <returns>
           <see langword="true" /> if the specified value is a power of two; <see langword="false" /> otherwise.</returns>
         <remarks>To be added.</remarks>