Make clear that you can try the demo online.

It's not necessary to download the source and build it if you just
want to see the emulator running.  Provide a link to the online demo.

Author: youngman-g

README.md

@@ -14,8 +14,12 @@ From [the Wikipedia entry for the TX-2](https://en.wikipedia.org/wiki/TX-2):
 
 ## Trying It Out
 
-To get started with using the emulator, please read [Getting
-Started](docs/getting-started.md).
+You can [try out an online demo](https://tx-2.github.io/demo/).  This
+runs locally in your browser.
+
+You can also check out a copy of the source code, and build and run
+the emulator yourself; to get started with using the emulator, please
+read [Getting Started](docs/getting-started.md).
 
 ## For More Information
 

docs/getting-started.md

@@ -1,5 +1,17 @@
 # Getting Started
 
+## Online Demo
+
+If you just want to see the emulator running, the simplest way is to
+use the [online demo](https://tx-2.github.io/demo/).  This runs
+locally in your browser.
+
+The rest of this document explains to build and run the emulator and
+its associated tools yourself, but you don't need to do that just to
+see it running.
+
+## Components of the TX-2 Emulator
+
 The TX-2 emulator repository includes several components:
 
 - Command-line tools for assembling, disassembling and inspecting TX-2