Docs/ExpectAPI: Correct docs for objectContaining (#6754)

## Summary

Found an error in the docs for `expect.objectContaining(object)` describing what properties are matched by the method. The previous sentence seem to have been copy/pasted from `expect.not.objectContaining(object)`.

CHANGELOG.md

@@ -6,6 +6,7 @@
 
 ### Fixes
 
+- `[docs]` Update `expect.objectContaining()` description ([#6754](https://github.com/facebook/jest/pull/6754))
 - `[babel-jest]` Make `getCacheKey()` take into account `createTransformer` options ([#6699](https://github.com/facebook/jest/pull/6699))
 - `[docs]` Fix contributors link ([#6711](https://github.com/facebook/jest/pull/6711))
 - `[website]` Fix website versions page to link to correct language ([#6734](https://github.com/facebook/jest/pull/6734))

docs/ExpectAPI.md

@@ -329,7 +329,7 @@ describe('not.stringMatching', () => {
 
 ### `expect.objectContaining(object)`
 
-`expect.objectContaining(object)` matches any received object that recursively matches the expected properties. That is, the expected object is a **subset** of the received object. Therefore, it matches a received object which contains properties that are **not** in the expected object.
+`expect.objectContaining(object)` matches any received object that recursively matches the expected properties. That is, the expected object is a **subset** of the received object. Therefore, it matches a received object which contains properties that **are present** in the expected object.
 
 Instead of literal property values in the expected object, you can use matchers, `expect.anything()`, and so on.
 

website/versioned_docs/version-23.3/ExpectAPI.md

@@ -330,7 +330,7 @@ describe('not.stringMatching', () => {
 
 ### `expect.objectContaining(object)`
 
-`expect.objectContaining(object)` matches any received object that recursively matches the expected properties. That is, the expected object is a **subset** of the received object. Therefore, it matches a received object which contains properties that are **not** in the expected object.
+`expect.objectContaining(object)` matches any received object that recursively matches the expected properties. That is, the expected object is a **subset** of the received object. Therefore, it matches a received object which contains properties that **are present** in the expected object.
 
 Instead of literal property values in the expected object, you can use matchers, `expect.anything()`, and so on.