Update 1.create-space.md (#1349)

docs-2.0/3.ngql-guide/9.space-statements/1.create-space.md

@@ -34,12 +34,17 @@ CREATE SPACE [IF NOT EXISTS] <graph_space_name> (
 
 !!! caution
 
-    If the replica number is set to one, you will not be able to load balance or scale out the Nebula Graph Storage Service with the [BALANCE](../../8.service-tuning/load-balance.md) statement.
-
-!!! caution "Restrictions on VID type change and VID length"
+    - If the replica number is set to one, you will not be able to load balance or scale out the Nebula Graph Storage Service with the [BALANCE](../../8.service-tuning/load-balance.md) statement.
+  
+    - Restrictions on VID type change and VID length:
 
-    The length of the VID should not be longer than `N` characters. If it exceeds `N`, Nebula Graph throws `The VID must be a 64-bit integer or a string fitting space vertex id length limit.`.
+      - For Nebula Graph v1.x, the type of VIDs can only be `INT64`, and the String type is not allowed. For Nebula Graph v2.x, both `INT64` and `FIXED_STRING(<N>)` VID types are allowed. You must specify the VID type when creating a graph space, and use the same VID type in `INSERT` statements, otherwise, an error message `Wrong vertex id type: 1001` occurs.
+
+      - The length of the VID should not be longer than `N` characters. If it exceeds `N`, Nebula Graph throws `The VID must be a 64-bit integer or a string fitting space vertex id length limit.`.
+
+!!! compatibility "Legacy version compatibility"
 
+    For Nebula Graph v2.x before v2.5.0, `vid_type` is optional and defaults to `FIXED_STRING(8)`.
 
 !!! note