Clarify inspect documentation

Signed-off-by: Phong Tran <tran.pho@northeastern.edu>

docs/reference/buildx_inspect.md

@@ -43,6 +43,10 @@ name of the builder to inspect to get information about that builder.
 The following example shows information about a builder instance named
 `elated_tesla`:
 
+> **Note**
+> 
+> Asterisk `*` next to node build platform(s) indicate they had been set manually during `buildx create`. Otherwise, it had been autodetected.
+
 ```console
 $ docker buildx inspect elated_tesla
 
@@ -58,5 +62,5 @@ Platforms: linux/amd64
 Name:      elated_tesla1
 Endpoint:  ssh://ubuntu@1.2.3.4
 Status:    running
-Platforms: linux/arm64, linux/arm/v7, linux/arm/v6
+Platforms: linux/arm64*, linux/arm/v7, linux/arm/v6
 ```