Jinja2 is being renamed to 'Jinja'

[geerlingguy]

See:

• Jinja2 renaming to Jinja ansible/ansible#66163
• Rename jinja2 to jinja pallets/jinja#1121

In the book, there are multiple references to "Jinja2", which I should update and rename to just "Jinja".

[geerlingguy]

One interesting side effect... all the stuff in Ansible (including my book and most of my example playbooks and such) use the .j2 extension to indicate 'Jinja2' templates... I'm probably going to leave that alone for now, since that's a more seismic change—but it looks like according to a recent docs change, the .jinja extension may be the recommended Jinja-specific file extension.

[geerlingguy]

Fixed the plain text references, and opened a follow-up for changing file names: #199

[davidism]

Just a heads up, since I saw this linked from the Jinja issue: We're no longer planning to rename the package or imports, they will remain jinja2.