Update README to reflect current status (#57)

This track has one exercise, no maintainers, and no activity
for a very long time.

Let's archive the repository.

README.md

@@ -1,26 +1,8 @@
 # Exercism ARM64 Assembly Track
 
-[![Build Status](https://travis-ci.org/exercism/arm64-assembly.svg?branch=master)](https://travis-ci.org/exercism/arm64-assembly)
+## Status
 
-Exercism exercises in ARM64 Assembly.
+Some work has been done to configure this track.
+It has only one exercise (`hello-world`).
 
-## Assembler
-
-GNU Assembler (gas) is used for this track.
-
-## Testing
-
-Unity is a simple unit testing framework for C used by this track.
-Using a framework written in C instead of assembly language is easier to understand.
-It also shows how parameters are passed when calling assembly routines from C.
-
-## Variant and Calling Conventions
-
-This is probably going to use the ARMv8.0-A profile which is a good default.
-This track is also probably going to use the ARM default calling convention to spare mentors from trouble.
-
-## Contributing Guide
-
-Please see the [contributing guide][contributing-guide]
-
-[contributing-guide]: https://github.com/exercism/x-api/blob/master/CONTRIBUTING.md#the-exercise-data
+If you wish to work on this track, please post in the [Exercism Community Forum](https://forum.exercism.org/c/exercism/building-exercism/125) to discuss it with the team.