Updated README with run instructions

- README now tells how to run pizza from bare repo

 - README tells dependency on a running mail delivery service

README

@@ -1,3 +1,9 @@
 Ever wanted to share a pizza (or else) to anyone who offers a service, for example hosts a data sharing service?
 
 With PIZZA, you may now send pizza (or else) to any mailaddress out there!
+
+Usage: You need a running mail-service on your system (i.e. a postfix configured to use a smarthost).
+To run "pizza" from the bare repository, cd into the src directory and run
+
+export PIZZAINC="../assets"; ./pizza
+

src/pizza

@@ -21,7 +21,7 @@ else
             mail -s "${PIZZAUSER} sent you a Pizza on ${PIZZAHOST}" $2 < "${PIZZAINC}/pizza"
             ;;
         "-l" | "--heart")
-            mail -s "${PIZZAUSER} sent you a Heart on ${PIZZAHOST}" $2 < "${PIZZAINC}/heart.txt"
+            mail -s "${PIZZAUSER} sent you a Heart on ${PIZZAHOST}" $2 < "${PIZZAINC}/heart"
             ;;
         "-h" | "--help")
             help