I propose to create a summary on the top of the policy to summarize main directives explained in the policy, something like did Legal Department with Privacy policy or Trademark policy. This would emphasize main ideas, and can be a quick-read for casual extensions developers. I quickly re-read the current version of the policy and wrote the following example to give a example of such a summary; obviously it should be more carefully written and phrased, and perhaps written when the final policy is fixed.
« MediaWiki core developers should follow the deprecation process above, upon exceptional circonstances. The main directives are: analyse impacts, document, and advertize. Two deprecation steps are introduced: soft deprecation (add @deprecated annotations) and hard deprecation (emit deprecation notices). Deprecations must be mentioned in the RELEASE-NOTES file and in documentation, and may be advertised elsewhere. Any code in core or extensions reaching deprecated code should be rewritten. Removal of code cannot be done unless it was hard-deprecated since "one" ("two" recommanded) stable versions. »