use MH instead of NUTS to avoid triggering ForwardDiff error

Author: penelopeysm

developers/compiler/model-manual/index.qmd

@@ -66,7 +66,7 @@ model2 = gdemo2([1.5, 2.0])
 We can sample from this model in the same way:
 
 ```{julia}
-chain = sample(model2, NUTS(), 1000; progress=false)
+chain = sample(model2, MH(), 1000; progress=false)
 ```
 
 The subsequent pages in this section will show how the `@model` macro does this behind-the-scenes.