Clarify docs for Leading/TrailingZeroCount (dotnet#8643)

Author: dakersnar

xml/System.Numerics/IBinaryInteger`1.xml

@@ -198,9 +198,9 @@
         <Parameter Name="value" Type="TSelf" />
       </Parameters>
       <Docs>
-        <param name="value">The value whose leading zeroes are to be counted.</param>
-        <summary>Computes the number of leading zeros in a value.</summary>
-        <returns>The number of leading zeros in <paramref name="value" />.</returns>
+        <param name="value">The value whose leading zero bits are to be counted.</param>
+        <summary>Computes the number of leading zero bits in a value.</summary>
+        <returns>The number of leading zero bits in <paramref name="value" />.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -486,9 +486,9 @@
         <Parameter Name="value" Type="TSelf" />
       </Parameters>
       <Docs>
-        <param name="value">The value whose trailing zeroes are to be counted.</param>
-        <summary>Computes the number of trailing zeros in a value.</summary>
-        <returns>The number of trailing zeros in <paramref name="value" />.</returns>
+        <param name="value">The value whose trailing zero bits are to be counted.</param>
+        <summary>Computes the number of trailing zero bits in a value.</summary>
+        <returns>The number of trailing zero bits in <paramref name="value" />.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>