chore(workflow): add exec/logs docs

Author: duanhongyi

src/applications/managing-app-lifecycle.md

@@ -105,7 +105,7 @@ from every [Container][] making it easy to troubleshoot problems with your appli
 
 Use `drycc logs` to view the log output from your deployed application.
 
-    $ drycc logs | tail
+    $ drycc logs -f
     Dec  3 00:30:31 ip-10-250-15-201 peachy-waxworks[web.5]: INFO:oejsh.ContextHandler:started o.e.j.s.ServletContextHandler{/,null}
     Dec  3 00:30:31 ip-10-250-15-201 peachy-waxworks[web.8]: INFO:oejs.Server:jetty-7.6.0.v20120127
     Dec  3 00:30:31 ip-10-250-15-201 peachy-waxworks[web.5]: INFO:oejs.AbstractConnector:Started SelectChannelConnector@0.0.0.0:10005

src/applications/managing-app-processes.md

@@ -214,6 +214,38 @@ echoed-lollipop-web-67cfc78bdc-fdx4n up (v2)
 echoed-lollipop-web-67cfc78bdc-h2vxf up (v2)
 ```
 
+## Get a Shell to a Running Container
+
+Verify that the container is running:
+
+```
+# drycc ps
+=== python-getting-started Processes
+--- web:
+python-getting-started-web-69b7d4bfdc-kl4xf up (v2)
+```
+
+Get a shell to the running container:
+
+```
+# drycc ps:exec python-getting-started-web-69b7d4bfdc-kl4xf -it -- bash
+```
+
+In your shell, list the root directory:
+
+```
+# Run this inside the container
+ls /
+```
+
+Running individual commands in a container
+
+```
+# drycc ps:exec python-getting-started-web-69b7d4bfdc-kl4xf -- date
+```
+
+Use "drycc ps --help" for a list of global command-line (applies to all commands).
+
 ## Autoscale
 
 Autoscale allows adding a minimum and maximum number of pods on a per process type basis. This is accomplished by specifying a target CPU usage across all available pods.