Clarify the use of the license key command-line option.

docs/command-line.md

@@ -110,7 +110,7 @@ The command-line may include the options described below:
     </dd>
     <dt id="cl-license-key"><code>--license-key=<span class="replaceable">KEY</span></code></dt>
     <dd>
-    Pass the license key on the command line. The <code>&lt;signature&gt;</code> element from your license file needs to be deleted, and its value can then be passed as the value of this command-line option. It is handy when you don't want to ship a product with the license key.
+    Pass the license key on the command line - this is useful if you don't want to ship a product with the license key. The contents of the <code>&lt;signature&gt;</code> element must be deleted from your license file, and its value can then be passed as the value of this command-line option - but leave an empty <code>&lt;signature&gt;</code> element in place.
     </dd>
 </dl>
 

docs/server-integration.md

@@ -778,6 +778,10 @@ As a general rule, consider that, in order to function best, Prince will need to
 For ease of use, Prince offers its own, maintained [Docker Images](https://hub.docker.com/r/yeslogic/prince).  See also [Prince In Cloud Computing](#prince-in-cloud-computing) for more installation guides in cloud containers.
 
 
+### License Files in Distributed Products
+
+When creating a product for distribution, it might be that you do not want to ship a license file with the distribution - but nevertheless be able to run Prince with a license file when necessary.  In this case the command-line option [`--license-key`](command-line.md#cl-license-key) might come in handy.  The contents of the `<signature>` element must be deleted from your license file, and its value can then be passed as the value of this command-line option - but leave an empty `<signature>` element in place.
+
 
 
 Performance