Update README.md

Add a note on what languages to use.

README.md

@@ -6,19 +6,18 @@ handbook](https://about.gitlab.com/handbook/).
 ## Introduction
 
 The Shorebird handbook is the central repository of how we run the company.  It
-is a living document that is updated as we learn and grow.  It is a work in
-progress, and we welcome your feedback and contributions.
+is a living document that is updated as we learn and grow.  We welcome your
+feedback and contributions.
 
 ## About Shorebird
 
 Shorebird (legally Code Town, Inc) is a Delaware C Corp, founded to foster
 adoption of multi-platform development globally.  We were founded by some of the
 same team who built Flutter and Dart and use those as our vehicle.
 
-Shorebird is likely a placeholder name until we find a better one.  Suggestions
-welcome.
+Shorebird is the name of the street on which Flutter was created and is likely a
+placeholder name until we find a better one.  Suggestions welcome.
 
-Shorebird is the name of the street on which Flutter was created.
 
 ## Mission
 
@@ -155,6 +154,22 @@ argument as to why something else should be higher on the list.  Adam Barth
 list of what we saw was the most important things for the project and pick
 things off the list and do them.
 
+### Languages
+Where possible we use Dart.  "Dart as a single language everywhere" is part of
+the dream we sell our customers and we should eat that dogfood.  That will cause
+us to use a bunch of unfinished parts of the Dart ecosystem and find ourselves
+building out parts where we need, but that's OK.
+
+We're also practical and when Dart isn't the best choice (e.g. for parts of the
+engine) we'll use languages we need to get the job done.  We will prefer to use
+languages built in the last decade (e.g. rust, zig, etc) rather than older
+less-safe/harder-to-use languages (e.g. c, c++), but we're not dogmatic about
+this.
+
+Rarely, we will write in the single-system languages (e.g. Kotlin, Swift, Java,
+etc.) that don't port to other places.  We do that to save time for our
+customers.
+
 ### Open Source
 Following our "be open" value, we default all our source code to being open and
 licensed as permissively as possible.