Add shebang to examples

examples/advanced/01_DocumentConverter/DocumentConverter.pow

@@ -1,3 +1,5 @@
+#!/bin/sh
+
 kapow route add '/format/input' - <<-'EOF'
 	kapow set /response/headers/Content-Type application/json
 	pandoc --list-input-formats \

examples/advanced/02_NetworkScanner/NetworkScanner.pow

@@ -1,3 +1,5 @@
+#!/bin/sh
+
 kapow route add -X POST '/scan' - <<-'EOF'
 	PORTS=$(kapow get /request/form/ports)
 	IP=$(kapow get /request/form/ip)

examples/advanced/03_NetworkSniffer/NetworkSniffer.pow

@@ -1 +1,3 @@
+#!/bin/sh
+
 kapow route add /sniff -c 'tcpdump -i any -U -s0 -w - "not portrange 8080-8082" | kapow set /response/body'