Update whatsnew and README.md.

README.md

@@ -138,7 +138,9 @@ displays the "This will install..." and /HELP message boxes.
 
 **ISSigTool** - This is a command-line tool which can be used to sign and verify
 any file. Compil32, ISCC, and ISCmplr use these signatures to verify the
-authenticity of a number of DLL files before loading them.
+authenticity of a number of DLL files before loading them. Note: this tool does
+not replace Microsoft's signtool.exe in any way and is in fact not related to
+Authenticode Code Signing at all.
 
 How do the projects link together?
 

whatsnew.htm

@@ -32,6 +32,7 @@ For conditions of distribution and use, see <a href="files/is/license.txt">LICEN
 <p><a name="6.4.3"></a><span class="ver">6.4.3-dev </span><span class="date">(?)</span></p>
 <ul>
   <li>Compiler IDE change: The editor now restores selections on undo and redo.</li>
+  <li>Inno Setup now includes a new Signature Tool, ISSigTool.exe. This is a command-line tool which can be used to sign and verify any file. Compil32, ISCC, and ISCmplr use these signatures to verify the authenticity of a number of DLL files before loading them. Note: this tool does not replace Microsoft's signtool.exe in any way and is in fact not related to Authenticode Code Signing at all.</li>
 </ul>
 
 <p><a name="6.4.2"></a><span class="ver">6.4.2 </span><span class="date">(2025-03-12)</span></p>