add changelog & man page changes

Author: melsonic

ci/release/changelogs/next.md

@@ -24,6 +24,9 @@
   - Support relative imports. Improve elk error handling: [#2382](https://github.com/terrastruct/d2/pull/2382)
   - Support fonts (`fontRegular`, `fontItalic`, `fontBold`, `fontSemiBold`): [#2384](https://github.com/terrastruct/d2/pull/2384)
 
+- d2cli:
+    - Support `validate` command. [#2415](https://github.com/terrastruct/d2/pull/2415)
+
 #### Bugfixes ⛑️
 
 - Compiler:

ci/release/template/man/d2.1

@@ -17,6 +17,8 @@
 .Ar fmt Ar file.d2 ...
 .Nm d2
 .Ar play Ar file.d2
+.Nm d2
+.Ar validate Ar file.d2 ...
 .Sh DESCRIPTION
 .Nm
 compiles and renders
@@ -162,6 +164,8 @@ Lists available themes
 Format all passed files
 .It Ar play Ar file.d2
 Opens the file in playground, an online web viewer (https://play.d2lang.com)
+.It Ar validate Ar file.d2 ...
+Validate all input files
 .El
 .Sh ENVIRONMENT VARIABLES
 Many flags can also be set with environment variables.