fix: changelog bullets in AIPs 213 and 215. (#1175)

Author: metamatt

aip/general/0213.md

@@ -214,9 +214,9 @@ have organization-specific use cases which surface through the components.
 
 ## Changelog
 
-- 2023-06-XX: Restructured AIPs 215 and 213 for clarity, and introduced the
+- **2023-06-27**: Restructured AIPs 215 and 213 for clarity, and introduced the
   concept of organization-wide common protos more formally.
-- 2018-08-17: Initial AIP written.
+- **2018-08-17**: Initial AIP written.
 
 [open an issue]: https://github.com/googleapis/aip/issues
-[aip-215]: ./0215.md
+[aip-215]: ./0215.md

aip/general/0215.md

@@ -55,9 +55,9 @@ they can still diverge over time as they are isolated from each other.
 
 ## Changelog
 
-2023-06-XX: Restructured AIPs 215 and 213 for clarity.
-2023-05-11: Changed "PA" to "organization".
-2018-10-01: Initial AIP written.
+- **2023-06-27**: Restructured AIPs 215 and 213 for clarity.
+- **2023-05-11**: Changed "PA" to "organization".
+- **2018-10-01**: Initial AIP written.
 
 [aip-213]: ./0213.md
 [aip-122]: ./0122.md