fix manual Model invocation

Author: penelopeysm

developers/compiler/model-manual/index.qmd

@@ -54,7 +54,7 @@ function gdemo2(model, varinfo, x)
     # value and the updated varinfo.
     return nothing, varinfo
 end
-gdemo2(x) = DynamicPPL.Model(gdemo2, (; x))
+gdemo2(x) = DynamicPPL.Model{false}(gdemo2, (; x))
 
 # Instantiate a Model object with our data variables.
 model2 = gdemo2([1.5, 2.0])
@@ -66,4 +66,4 @@ We can sample from this model in the same way:
 chain = sample(model2, NUTS(), 1000; progress=false)
 ```
 
-The subsequent pages in this section will show how the `@model` macro does this behind-the-scenes.
+The subsequent pages in this section will show how the `@model` macro does this behind-the-scenes.