docs: Update App Widgets dev guide size discussion
docs: Update App Widgets dev guide size discussion

This is mainly an update to match the design guidelines.
See also bug 5555264.

Change-Id: I1c83fb33b7dca412905d21b588c5754d1d3c5cfe

xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base