document levels of adoption

Author: swyxio

MIGRATING.md

@@ -6,13 +6,23 @@ This Cheatsheet collates advice and utilities from real case studies of teams mo
 
 ## General Conversion approaches
 
+- Level 0: Don't use TypeScript, use JSDoc
+  - See our [JSDoc section](#JSDoc)
+- Level 1: Unstrict TypeScript
+  - `"noImplicitAny": false`
+  - "[Just rename all .js files to .ts](https://twitter.com/jamonholmgren/status/1089241726303199232)"
+  - consider using `allowJS`? (Source: [clayallsop][clayallsop], [pleo][pleo])
+- Level 2: Strict TypeScript
+  - use Microsoft's [`dts-gen`](https://github.com/Microsoft/dts-gen) to generate `.d.ts` files for your untyped files. [This SO answer](https://stackoverflow.com/questions/12687779/how-do-you-produce-a-d-ts-typings-definition-file-from-an-existing-javascript) has more on the topic.
+  - use `declare` keyword for ambient declarations
+  
+
+Misc tips/approaches successful companies have taken
+
 - `@ts-ignore` on compiler errors for libraries with no typedefs
 - pick ESLint over TSLint ([source](https://eslint.org/blog/2019/01/future-typescript-eslint))
 - New code must always be written in TypeScript. No exceptions. For existing code: If your task requires you to change JavaScript code, you need to rewrite it. (Source: [Hootsuite][hootsuite])
-- consider using `allowJS`? (Source: [clayallsop][clayallsop], [pleo][pleo])
-- consider `"noImplicitAny": false` if you need a gentler onboarding
-- use Microsoft's [`dts-gen`](https://github.com/Microsoft/dts-gen) to generate `.d.ts` files for your untyped files. [This SO answer](https://stackoverflow.com/questions/12687779/how-do-you-produce-a-d-ts-typings-definition-file-from-an-existing-javascript) has more on the topic.
-- use `declare` keyword for ambient declarations
+
 
 <details>
 <summary>