Added examples on how to reference request metadata

Author: erwinvaneyk

examples/misc/inputs.wf.yaml

@@ -0,0 +1,9 @@
+# The Inputs Workflow - simply prints the inputs it received, including body, query params and headers.
+#
+# Example: curl -XPUT -H "hello: world" http://$FISSION_ROUTER/fission-function/inputs?a=b
+apiVersion: 1
+output: Printer
+tasks:
+  Printer:
+    run: compose
+    inputs: "{$.Invocation.Inputs}"

examples/whales/metadatawhale.wf.yaml

@@ -5,4 +5,6 @@ tasks:
   PrefixedFortune:
     run: fortune
     inputs:
-      header_prefix: "Whale says:"
+      headers:
+        # If the 'prefix' header is non-empty, we use that. Otherwise we default to "whale says"
+        prefix: "{ $.Invocation.Inputs.headers.Prefix || 'Whale says: ' }"