message: Add documention for new tsConfig
diff: @@ -114,13 +114,15 @@ If the default setup doesn't address your requirements, you can create a custom
  By default this package will try to locate `tsconfig.json` and use its compiler options for your `.ts` and `.tsx` files.
  You can override this behaviour by pointing ts-jest to a custom TypeScript configuration file.
  -You can do this by setting the `__TS_CONFIG__` option in globals for jest to the path of the
  -custom configuration file (relative to the project's root directory)```json
  -```
  +You can do this by setting the `tsConfigFile` option in your global variables under the `ts-jest` key to path of the
  +custom configuration file (relative to the project's root directory) (__TS_CONFIG__ is deprecated)
  +```json
  {
  "jest": {
  "globals": {
  - "__TS_CONFIG__": "my-tsconfig.json"
  + "ts-jest": {
  + "tsConfigFile": "my-tsconfig.json"
  + }
  }
  }
  }
  @@ -130,17 +132,21 @@ Or even declare options for `tsc` instead of using separate config, like this:
  {
  "jest": {
  "globals": {
  - "__TS_CONFIG__": {
  + "ts-jest": {
  + "tsConfig": {
  "module": "commonjs",
  "jsx": "react"
  }
  }
  }
  }
  +}
  ```
  +**Warning: Using __TS_CONFIG__ option in globals is deprecated and soon will be removed.**
  +
  For all available `tsc` options see [TypeScript docs](https://www.typescriptlang.org/docs/handbook/compiler-options.html).
  -Note that if you haven't explicitly set the `module` property in the `__TS_CONFIG__` setting (either directly or through a separate configuration file), it will be overwritten to `commonjs` (regardless of the value in `tsconfig.json`) since that is the format Jest expects. This only happens during testing.
  +Note that if you haven't explicitly set the `module` property in the `tsConfig` setting (either directly or through a separate configuration file with `tsConfigFile`), it will be overwritten to `commonjs` (regardless of the value in `tsconfig.json`) since that is the format Jest expects. This only happens during testing.
  ### Skipping Babel
  If you don't use mocks, or synthetic default imports you can skip the babel-transpilation step.
  