Update release notes before release (#54)

Update before next release that adds resampling option according to
https://github.com/frequenz-floss/frequenz-client-reporting-python/blob/v0.x.x/CONTRIBUTING.md#releasing.

Author: flora-hofmann-frequenz

RELEASE_NOTES.md

@@ -2,17 +2,13 @@
 
 ## Summary
 
-<!-- Here goes a general summary of what this release is about -->
-
 ## Upgrading
 
-<!-- Here goes notes on how to upgrade from previous versions, including deprecations and what they should be replaced with -->
-
 ## New Features
 
 * The `ReportingApiClient` exposes the resampling option of the data, with its 
-resolution represented in second and its default set to `None.
+resolution represented in second and its default set to `None`.
 
-## Bug Fixes
+* Updated README with usage instructions.
 
-<!-- Here goes notable bug fixes that are worth a special mention or explanation -->
+## Bug Fixes