Prepare for v1.0.0-rc1900 (#1218)

Author: shsms

RELEASE_NOTES.md

@@ -2,7 +2,7 @@
 
 ## Summary
 
-<!-- Here goes a general summary of what this release is about -->
+This release introduces a number of breaking changes in the config manager, the new `ComponentId`/`MicrogridId` types and the `numpy` version update.  It also includes bug-fixes to the component graph and power management.
 
 ## Upgrading
 
@@ -41,10 +41,6 @@
 
 * The SDK now depends on the `frequenz-client-microgrid` v0.7.x series. The main change is now all component and microgrid IDs need to be passed using the wrapper classes `ComponentId`/`MicrogridId` instead of `int`.
 
-## New Features
-
-<!-- Here goes the main new features and examples or instructions on how to use them -->
-
 ## Bug Fixes
 
 - The power manager used to just forgot components when all proposals to them are withdrawn, leaving them at their last set power values.  This has been fixed by getting the power manager to set the components to their default powers, based on the component category (according to the table below), as the last step.