Update CHANGELOG/README for v0.3.0

CHANGELOG.md

@@ -1,3 +1,9 @@
+## v0.3.0
+
+* Add ability to profile subprocesses [#124](https://github.com/benfred/py-spy/issues/124)
+* Fix overflow issue with linux symbolication [#183](https://github.com/benfred/py-spy/issues/183)
+* Fixes for printing local variables [#180](https://github.com/benfred/py-spy/pull/180)
+
 ## v0.2.2
 
 * Add ability to show local variables when dumping out stack traces [#77](https://github.com/benfred/py-spy/issues/77)

README.md

@@ -51,8 +51,7 @@ You can change the file format to generate
 [speedscope](https://github.com/jlfwong/speedscope) profiles or raw data with the ```--format``` parameter.
 See ```py-spy record --help``` for information on other options including changing
 the sampling rate, filtering to only include threads that hold the GIL, profiling native C extensions,
-showing thread-ids and more.
-
+showing thread-ids, profiling subprocesses and more.
 
 ### top
 
@@ -132,6 +131,15 @@ noting for Cython programs is that py-spy needs the generated C or C++ file in o
 numbers of the original .pyx file.  Read the [blog post](https://www.benfrederickson.com/profiling-native-python-extensions-with-py-spy/)
 for more information.
 
+### How can I profile subprocesses?
+
+By passing in the ```--subprocesses``` flag to either the record or top view, py-spy will also include
+the output from any python process that is a child process of the target program. This is useful
+for profiling applications that use multiprocessing or gunicorn worker pools. py-spy will monitor
+for new processes being created, and automatically attach to them and include samples from them in
+the output. The record view will include the PID and cmdline of each program in the callstack,
+with subprocesses appearing as children of their parent processes.
+
 ### When do you need to run as sudo?
 
 py-spy works by reading memory from a different python process, and this might not be allowed for security reasons depending on