update changelog

doc/source/changelog.rst

@@ -3,19 +3,17 @@ Changelog
 
 - **v0.9.0** (*2018-11-19*):
 
-    - Use ``psutil`` to track aggregate memory usage for processes that spawn children
+    - Use ``psutil`` to track aggregate memory usage for processes that spawn
+    children. This results in accurate memory records for these processes.
 
-    - Implement pipes in python so that individual commands in a series of shell 
-      pipes that fail will now also halt the pipeline, instead of proceeding
-      with potentially bad files.
+    - Individual commands in a string of commands connected by shell pipes are
+    now treated as individual commands, and and monitored individually for
+    time and memory, and if a single component, fails, the entire string will
+    fail. Previously, only the final return command was recorded, as in ``bash``.
 
     - Various other small improvements (like waiting checking for dynamic recover
-      flags)
-
-    - Improved the ``run`` waiting method to immediately stop upon job
-      completion, rather than minute-increment polling. This should improve
-      performance particularly in pipelines with many, medium-runtime steps, and
-      improve accuracy of timing profiles.
+    flags)
+
 
 - **v0.8.1** (*2018-09-20*):