fix example lint

recipes/example-v1/recipe.yaml

@@ -6,7 +6,7 @@
 # The main differences with the old format is that no preprocessing is required for the file to be valid YAML.
 # This means:
 # - No "selectors", use YAML if-then-else expressions instead (https://prefix-dev.github.io/rattler-build/latest/selectors/)
-# - Jinja expressions are formatted with `${{}}`
+# - Jinja expressions are formatted with a leading `$` to make them valid YAML
 
 # Note: there are many handy hints in comments in this example -- remove them when you've finalized your recipe