xhttp_pi: documentation updates

modules/xhttp_pi/README

@@ -260,8 +260,8 @@ modparam("xhttp_pi", "xhttp_pi_root", "pi")
 
 6.2. xhttp_pi_buf_size (int)
 
-   It specifies the maximum length of the buffer used to write in the HTML
-   reply information in order to build the HTML response.
+   It specifies the maximum length of the buffer (in bytes) used to write
+   in the HTML reply information in order to build the HTML response.
 
    Default value is 0 (auto set to 1/3 of the size of the configured pkg
    mem).

modules/xhttp_pi/doc/xhttp_pi_admin.xml

@@ -301,7 +301,7 @@ modparam("xhttp_pi", "xhttp_pi_root", "pi")
 	<section>
 		<title><varname>xhttp_pi_buf_size</varname> (int)</title>
 		<para>
-			It specifies the maximum length of the buffer used
+			It specifies the maximum length of the buffer (in bytes) used
 			to write in the HTML reply information in order to
 			build the HTML response.
 		</para>