docs) add hello world welcome note

HELLOWORLD.md

@@ -1,11 +1,7 @@
-Hello and welcome to the trips project!
+Hello and welcome to the Trips project!
 
-We are glad you are here. This repository exists to help you build and
-improve travel experiences, and your contributions make it better for
-everyone.
+We're glad you're here. This repository is the home for the Trips application and the tools that support it.
 
-If you are new, start by reading the README and checking the scripts and
-configuration files to understand how the project is set up. Then pick an
-issue or improvement you are interested in and dive in.
+If you're new, start with `README.md` to get the project running, then take a look around `src/` to see how things are organized.
 
-Thanks for being part of the team and happy coding!
+Happy building!