Bump per-user config file version to 20

Incremented version number in FirstRun.UConfigFile unit so that first
run of CodeSnip v 4.26.0 will record version 20 in the config file.

Also updated config file docs to refer to version 20.

Author: delphidabbler

Docs/Design/FileFormats/config.html

@@ -167,7 +167,7 @@ <h3>
 </p>
 
 <p>
-  There have been several versions of this file. The current one is version 19. The change to version 19 came with CodeSnip v4.21.0 and the addition of the [Compilers] section and the <code class="key">CanAutoInstall</code> key in the [Cmp:XXX] sections.
+  There have been several versions of this file. The current one is version 20. The change to version 20 came with CodeSnip v4.26.0 and the addition of the <code class="key">UseCommentsInUnitImpl</code> key in the <code>[Prefs:SourceCode]</code> section.
 </p>
 
 <p>
@@ -771,7 +771,7 @@ <h4>
       The version number of the config file. Incremented whenever the file format changes. If this section or this value is missing then the default value is <code class="value">1</code>.
     </div>
     <div class="half-spaced">
-      The current value is <code class="value">19</code>.
+      The current value is <code class="value">20</code>.
     </div>
   </dd>
   <dt>

Src/FirstRun.UConfigFile.pas

@@ -82,7 +82,7 @@   TUserConfigFileUpdater = class(TConfigFileUpdater)
   strict private
     const
       ///  <summary>Current user config file version.</summary>
-      FileVersion = 19;
+      FileVersion = 20;
   strict protected
     ///  <summary>Returns current user config file version.</summary>
     class function GetFileVersion: Integer; override;