update readme

typescript/README.md

@@ -22,3 +22,22 @@ const hello = ell.simple(
 
 const result = await hello({ firstName: 'John', lastName: 'Doe' })
 ```
+
+
+## Runtime and module support
+Ell TypeScript aims to support all JavaScript backend runtimes in addition to commonjs and ES modules.
+
+At the time of writing Node.js has full support for versinoning and tracing.
+
+Runtime variable capture depends on the `node:inspector` library or an equivalent. Vercel Edge runtime does not yet support this.
+
+## Developing
+
+Tests are currently written with two test frameworks, vitest and mocha.
+
+Vitest does not have accurate source maps, allowing us to simulate cases where a program's source maps are not available.
+There are a different set of expectations in this case, namely that the program does not blow up, but that lmps are not tracked or versioned.
+These tests end in `.test.ts`.
+
+Mocha tests use ts-node which we have found to have accurate source maps and is used for all tests that depend on them existing and being accurate.
+These tests end in `.mocha.ts`.