small darshan-runtime documentation changes

darshan-runtime/doc/darshan-runtime.txt

@@ -483,20 +483,17 @@ runtime environment variables] are equally applicable to both versions.
 However, we do provide some suggestions and expectations for system administrators to keep in
 mind when upgrading to Darshan 3.x:
 
-* Log file compatibility was broken in the upgrade, and thus 3.x log utilities do not
-work directly with logs generated by 2.x versions of Darshan (and vice versa).
-    - There is currently no tool for converting 2.x logs into the 3.x log format.
-    - The `darshan-logutils` library will provide error messages to indicate whether a given
+* Darshan 2.x and Darshan 3.x produce incompatible log file formats
+    ** log files named *.darshan.gz or *.darshan.bz2: Darshan 2.x format
+    ** log files named *.darshan: Darshan 3.x format
+        *** a field in the log file header indicates underlying compression method in 3.x logs
+    ** There is currently no tool for converting 2.x logs into the 3.x log format.
+    ** The `darshan-logutils` library will provide error messages to indicate whether a given
 log file is incompatible with the correspnonding library version. 
 
-* The darshan log file extension has been changed from `.darshan.gz` (or `.darshan.bz2` for
-log files converted to use bzip2 compression) to `.darshan`.
-    - A field in the Darshan log header is used to indicate whether a log is compressed using
-libz or bzip2 compression.
-
 * We encourage administrators to use the same log file directory for version 3.x as had been
 used for version 2.x.
-    - Within this directory, the determination on which set of log utilities (version 2.x
+    ** Within this directory, the determination on which set of log utilities (version 2.x
 or version 3.x) to use can be based on the file extension for a given log (as explained
 above).