add CURRENT.md to track major changes and how to migrate with them

CURRENT.md

@@ -0,0 +1,20 @@
+Active Metasploit 5 development will sometimes push aggressive changes.
+Integrations with 3rd-party tools, as well as general usage, may change quickly
+from day to day. Some of the steps for dealing with major changes will be
+documented here. We will continue to maintain the Metasploit 4.x branch until
+Metasploit 5.0 is released.
+
+**2018/01/17 - [internal] module cache reworked to not store metadata in PostgreSQL**
+
+Metasploit no longer stores module metadata in a PostgreSQL database, instead
+storing it in a cache file in your local ~/.msf4 config directory. This has a
+number of advantages:
+
+ * Fast searches whether you have the database enabled or not (no more slow search mode)
+ * Faster load time for msfconsole, the cache loads more quickly
+ * Private module data is not uploaded to a shared database, no collisions
+ * Adding or deleting modules no longer displays file-not-found error messages on start in msfconsole
+ * Reduced memory consumption
+
+Code that reads directly from the Metasploit database for module data will need
+to use the new module search API.