Add explicit Jinja2 requirement (#74)

Explicitly list Jinja2 `2.11.3` as a requirement, as well as detail the minimum supported version (`2.11.x`).

Author: alessfg

.github/workflows/requirements/requirements_molecule.txt

@@ -1,4 +1,5 @@
 ansible-base==2.10.7
+Jinja2==2.11.3
 ansible-lint==5.0.5
 yamllint==1.26.0
 molecule[docker]==3.3.0

CHANGELOG.md

@@ -14,6 +14,7 @@ FEATURES:
       - name: ansible.posix
         version: 1.2.0
     ```
+*   Explicitly list Jinja2 `2.11.3` as a requirement, as well as detail the minimum supported version (`2.11.x`).
 *   You can now specify an `nginx_app_protect_repository` for NGINX App Protect.
 *   You can now specify an `nginx_app_protect_security_updates_repository` for NGINX App Protect signatures and threat campaigns packages.
 *   You can now specify NGINX App Protect signatures and threat campaigns package versions using the `nginx_app_protect_signatures_version` and `nginx_app_protect_threat_campaigns_version` variables.

README.md

@@ -14,7 +14,8 @@ This role installs and configures NGINX App Protect (WAF) for NGINX Plus on your
 
 ### Ansible
 
-*   This role is developed and tested with [maintained](https://docs.ansible.com/ansible/devel/reference_appendices/release_and_maintenance.html) versions of Ansible base. When using Ansible base, you will also need to install the following collections:
+*   This role is developed and tested with [maintained](https://docs.ansible.com/ansible/devel/reference_appendices/release_and_maintenance.html) versions of Ansible base (bigger than `2.10`) and Ansible (bigger than `2.9.10`).
+*   When using Ansible base, you will also need to install the following collections:
     ```yaml
     ---
     collections:
@@ -23,12 +24,17 @@ This role installs and configures NGINX App Protect (WAF) for NGINX Plus on your
       - name: ansible.posix
         version: 1.2.0
     ```
-    **Note:** You can alternatively install the Ansible community distribution if you don't want to manage individual collections.
+    **Note:** You can alternatively install the Ansible community distribution (what is known as the "old" Ansible) if you don't want to manage individual collections.
 *   Instructions on how to install Ansible can be found in the [Ansible website](https://docs.ansible.com/ansible/latest/installation_guide/intro_installation.html#upgrading-ansible-from-version-2-9-and-older-to-version-2-10-or-later).
 
+### Jinja2
+
+*   This role uses Jinja2 templates. Ansible base installs Jinja2 by default, but depending on your install and/or upgrade path, you might be running an outdated version of Jinja2. The minimum version of Jinja2 required for the role to properly function is `2.11`.
+*   Instructions on how to install Jinja2 can be found in the [Jinja2 website](https://jinja.palletsprojects.com/en/2.11.x/intro/#installation).
+
 ### Molecule
 
-*   Molecule `3.x` is used to test the various functionalities of the role.
+*   Molecule is used to test the various functionalities of the role. The recommended version of Molecule to test this role is `3.3`.
 *   Instructions on how to install Molecule can be found in the [Molecule website](https://molecule.readthedocs.io/en/latest/installation.html).
 *   To run the Molecule tests, you must first add your NGINX repository certificate and key to the local environment. Run the following commands to export these files as base64-encoded variables and execute the Molecule tests:
     ``` bash