Merge pull request #2701 from galacean/doc/multi-shader-syntax

fix: doc syntax

docs/en/graphics/material/shaderLab/multi.mdx

@@ -53,6 +53,8 @@ Additionally, the `UsePass` directive supports reusing built-in engine passes. C
 
 <Callout>
 The `SubShader` is not only used for organizing multiple passes but also supports setting `Tags`, which correspond to the engine's [setTag](/apis/galacean/#SubShader-setTag) API. For example, setting a `ReplaceTag`:
+</Callout>
+
 
 ```glsl showLineNumbers
 SubShader "SubShaderName" {
@@ -62,5 +64,4 @@ SubShader "SubShaderName" {
   Pass "PassName" {
     ...
   }
-}
-</Callout>
+}