docs: add CDX v2.0 in release history as "to be announced"

Signed-off-by: Jan Kowalleck <jan.kowalleck@gmail.com>

Author: jkowalleck

README.md

@@ -77,6 +77,7 @@ Alternatively, files that match the glob pattern below are also recognized:
 
 | Version           | Release Date    |
 |-------------------|-----------------|
+| CycloneDX 2.0     | to be announced |
 | CycloneDX 1.7     | 21 October 2025 |
 | CycloneDX 1.6     | 09 April 2024   |
 | CycloneDX 1.5     | 26 June 2023    |