Readme file update with 4.2 support details.

Author: psabhay

README.md

@@ -10,16 +10,16 @@ Ansible role which manages [MongoDB](http://www.mongodb.org/).
 
 MongoDB support matrix:
 
-| Distribution   | < MongoDB 3.2 |    MongoDB 3.4     |    MongoDB 3.6     |    MongoDB 4.0     |
-| -------------- | :-----------: | :----------------: | :----------------: | :----------------: |
-| Ubuntu 14.04   |  :no_entry:   | :white_check_mark: | :white_check_mark: | :white_check_mark: |
-| Ubuntu 16.04   |  :no_entry:   | :white_check_mark: | :white_check_mark: | :white_check_mark: |
-| Ubuntu 18.04   |  :no_entry:   |        :x:         | :white_check_mark: | :white_check_mark: |
-| Debian 8.x     |  :no_entry:   | :white_check_mark: | :white_check_mark: | :white_check_mark: |
-| Debian 9.x     |  :no_entry:   |        :x:         | :white_check_mark: | :white_check_mark: |
-| RHEL 6.x       |  :no_entry:   | :white_check_mark: | :white_check_mark: | :white_check_mark: |
-| RHEL 7.x       |  :no_entry:   | :white_check_mark: | :white_check_mark: | :white_check_mark: |
-| Amazon Linux 2 |  :no_entry:   | :white_check_mark: | :white_check_mark: | :white_check_mark: |
+| Distribution   | < MongoDB 3.2 |    MongoDB 3.4     |    MongoDB 3.6     |    MongoDB 4.0     |   MongoDB 4.2      |
+| -------------- | :-----------: | :----------------: | :----------------: | :----------------: | :----------------: |
+| Ubuntu 14.04   |  :no_entry:   | :white_check_mark: | :white_check_mark: | :white_check_mark: | :no_entry:         |
+| Ubuntu 16.04   |  :no_entry:   | :white_check_mark: | :white_check_mark: | :white_check_mark: | :white_check_mark: |
+| Ubuntu 18.04   |  :no_entry:   |        :x:         | :white_check_mark: | :white_check_mark: | :white_check_mark: |
+| Debian 8.x     |  :no_entry:   | :white_check_mark: | :white_check_mark: | :white_check_mark: | :no_entry:         |
+| Debian 9.x     |  :no_entry:   |        :x:         | :white_check_mark: | :white_check_mark: | :white_check_mark: |
+| RHEL 6.x       |  :no_entry:   | :white_check_mark: | :white_check_mark: | :white_check_mark: | :white_check_mark: |
+| RHEL 7.x       |  :no_entry:   | :white_check_mark: | :white_check_mark: | :white_check_mark: | :white_check_mark: |
+| Amazon Linux 2 |  :no_entry:   | :white_check_mark: | :white_check_mark: | :white_check_mark: | :white_check_mark: |
 
 - :white_check_mark: - fully tested, should works fine
 - :interrobang: - maybe works, not tested