Fix readonly version to julia 1.13+ and remove redundant [extras] compat

Author: gamila-wisam

docs/src/toml-files.md

@@ -112,7 +112,7 @@ the section on [pre-1.0 behavior](@ref compat-pre-1.0) for more details.
 ### The `readonly` field
 
 !!! compat
-    The `readonly` field requires Julia 1.12+.
+    The `readonly` field requires Julia 1.13+.
 
 The `readonly` field is a boolean that, when set to `true`, marks the environment as read-only. This prevents any modifications to the environment, including adding, removing, or updating packages. For example:
 
@@ -291,9 +291,6 @@ In this case, the workspaces are "merged" with a single manifest being stored al
 
 ### The `[extras]` section (legacy)
 
-!!! compat
-    Extras require Julia < 1.13; for Julia 1.13+ use [workspaces](@ref Workspaces).
-
 !!! warning
     The `[extras]` section is a legacy feature maintained for compatibility. For Julia 1.13+,
     using [workspaces](@ref Workspaces) is the recommended approach for managing test-specific