fix(docs): package.json config option (kulshekhar#823)

Document the package.json config option.

docs/user/config/index.md

@@ -193,6 +193,7 @@ All options have default values which should fit most of the projects. Click on
 | [**`diagnostics`**][diagnostics] | [Diagnostics related configuration.][diagnostics] | `boolean`\|`object` | `true` |
 | [**`babelConfig`**][babelConfig] | [Babel(Jest) related configuration.][babelConfig] | `boolean`\|`object` | _disabled_ |
 | [**`stringifyContentPathRegex`**][stringifyContentPathRegex] | [Files which will become modules returning self content.][stringifyContentPathRegex] | `string`\|`RegExp` | _disabled_ |
+| [**`packageJson`**][packageJson] | [Package metadata.][packageJson] | `string`\|`object`\|`boolean` | _auto_ |
 
 ### Upgrading
 
@@ -222,3 +223,4 @@ npx ts-jest config:migrate package.json
 [diagnostics]: diagnostics
 [babelConfig]: babelConfig
 [stringifyContentPathRegex]: stringifyContentPathRegex
+[packageJson]: packageJson

docs/user/config/packageJson.md

@@ -0,0 +1,69 @@
+---
+title: packageJson Config option
+---
+
+The `packageJson` option specifies the `package.json` file to use. An inline object may also be specified instead of a file path.
+
+By default, the `package.json` file at the root of the project will be used. If it cannot be found, an empty project definition will be used instead.
+
+### Examples
+
+#### Path to a `packageJson` file
+
+The path should be relative to the current working directory where you start Jest from. You can also use `<rootDir>` in the path to start from the project root dir.
+
+<div class="row"><div class="col-md-6" markdown="block">
+
+```js
+// jest.config.js
+module.exports = {
+  // [...]
+  globals: {
+    'ts-jest': {
+      packageJson: 'package.json'
+    }
+  }
+};
+```
+
+</div><div class="col-md-6" markdown="block">
+
+```js
+// OR from a non-trivial path
+// jest.config.js
+module.exports = {
+  // [...]
+  globals: {
+    'ts-jest': {
+      packageJson: '<rootDir>/../../shared/package.json'
+    }
+  }
+};
+```
+
+</div></div>
+
+#### Inline package metadata
+
+<div class="row"><div class="col-md-12" markdown="block">
+
+```js
+// jest.config.js
+module.exports = {
+  // [...]
+  globals: {
+    'ts-jest': {
+      packageJson: {
+          "name": "my-project",
+          "version": "1.0.0",
+          "dependencies": {
+            // [...]
+          }
+      }
+    }
+  }
+};
+```
+
+</div></div>
+