readme: update changelog tags to match filename tags

_dist/README.txt

@@ -14,7 +14,7 @@ Written in PHP, Bash
 
 =CHANGELOG=
 
-2015-11-08: r97
+2015-11-08: v97
 - Feature: Support BBCode b/i/spoiler/entry tags
 - Feature: Add more CSS styles to allow per-site customistaion
 - Feature: Use http://shields.io images where appropriate
@@ -22,23 +22,23 @@ Written in PHP, Bash
 - Fix an issue with project update-time detection
 - Fix a cosmetic issue with whitespace
 
-2015-04-05: r72
+2015-04-05: v72
 - Feature: Support redirecting old project names
 - Feature: Add file hash in download URLs to prevent filename collisions
 - Fix an issue generating spritesheets even if no project images are present
 - Don't include `ctime` when estimating project update time
 
-2015-04-05: r64
+2015-04-05: v64
 - Feature: Support sorting projects
 
-2015-04-04: r54
+2015-04-04: v54
 - Feature: Support multiple code sites
 - Fix an issue with parallel builds on some versions of windows
 - Fix an issue corrupting URL links with multiple parameters
 - Fix a cosmetic issue with page overflow
 - Fix a cosmetic issue with whitespace on code elements
 
-2014-07-02: r39
+2014-07-02: v39
 - Feature: Tags
 - Feature: Generate pages in parallel
 - Enhancement: Support raw HTML sections in page content
@@ -47,8 +47,8 @@ Written in PHP, Bash
 - Fix a cosmetic issue with download sort order
 - Fix a cosmetic issue with page layout
 
-2013-09-28: r13
+2013-09-28: v13
 - Initial public source code release
 
-2013-09-21: r3
+2013-09-21: v3
 - Initial deployment