docs: Add support schedule for v10 (angular#37745)

This commit adds the support schedule for v10.
v10.0.0 was released on June 24, 2020.
Active support ends six months later, on Dec 24, 2020.
Long term support ends a year after that, on Dec 24, 2021.

PR Close angular#37745

aio/content/guide/releases.md

@@ -101,6 +101,7 @@ The following table provides the status for Angular versions under support.
 
 Version | Status | Released     | Active Ends  | LTS Ends
 ------- | ------ | ------------ | ------------ | ------------
+^10.0.0 | Active | Jun 24, 2020 | Dec 24, 2020 | Dec 24, 2021
 ^9.0.0  | Active | Feb 06, 2020 | Aug 06, 2020 | Aug 06, 2021
 ^8.0.0  | LTS    | May 28, 2019 | Nov 28, 2019 | Nov 28, 2020