correct docs (#2466)

Author: Anipik

xml/System/Memory`1.xml

@@ -619,7 +619,7 @@ The garbage collector will not move the memory until the returned <xref:System.B
         <returns>An object that contains all elements of the current instance from <paramref name="start" /> to the end of the instance. </returns>
         <remarks>To be added.</remarks>
         <exception cref="T:System.ArgumentOutOfRangeExceptionException">
-          <paramref name="start" /> is less than zero or greater than or equal to <see cref="P:System.Memory`1.Length" />. </exception>
+          <paramref name="start" /> is less than zero or greater than <see cref="P:System.Memory`1.Length" />. </exception>
       </Docs>
     </Member>
     <Member MemberName="Slice">
@@ -686,7 +686,7 @@ The garbage collector will not move the memory until the returned <xref:System.B
         <returns>An object that contains <paramref name="length" /> elements from the current instance starting at <paramref name="start" />. </returns>
         <remarks>To be added.</remarks>
         <exception cref="T:System.ArgumentOutOfRangeExceptionException">
-          <paramref name="start" /> is less than zero or greater than or equal to <see cref="P:System.Memory`1.Length" />.
+          <paramref name="start" /> is less than zero or greater than <see cref="P:System.Memory`1.Length" />.
 
 -or-
 

xml/System/ReadOnlySpan`1.xml

@@ -783,7 +783,7 @@ A `ReadOnlySpan<T>` instance is often used to reference the elements of an array
         <returns>A read-only span that consists of <paramref name="length" /> elements from the current span starting at <paramref name="index" />.</returns>
         <remarks>To be added.</remarks>
         <exception cref="T:System.ArgumentOutOfRangeException">
-          <paramref name="start" /> is less than zero or greater than or equal to <see cref="T:System.Span`1.Length" />.</exception>
+          <paramref name="start" /> is less than zero or greater than <see cref="T:System.Span`1.Length" />.</exception>
       </Docs>
     </Member>
     <Member MemberName="ToArray">

xml/System/Span`1.xml

@@ -922,7 +922,7 @@ Two <xref:System.Span%601> objects are equal if they have different lengths or i
         <returns>A span that consists of all elements of the current span from <paramref name="index" /> to the end of the span.</returns>
         <remarks>To be added.</remarks>
         <exception cref="T:System.ArgumentOutOfRangeException">
-          <paramref name="index" /> is less than zero or greater than or equal to <see cref="T:System.Span`1.Length" />.</exception>
+          <paramref name="start" /> is less than zero or greater than <see cref="T:System.Span`1.Length" />.</exception>
       </Docs>
     </Member>
     <Member MemberName="Slice">