PHPLIB-596: Add tutorial for connecting to MongoDB

[alcaeus]

PHPLIB-596

This PR adds a small tutorial with information about connecting to MongoDB. The examples are taken from the documentation for MongoDB\Client::__construct, but provides them in a spot that should be easier to find.

Note: I haven't been able to build docs locally, and an attempt to build docs in a GitHub CI build also failed with the same error:

~/Code/mongodb/docs-php-library 
[master|✔] ❯❯❯ giza make html
Traceback (most recent call last):
  File "/opt/homebrew/bin/giza", line 5, in <module>
    from giza.cmdline import main
  File "/opt/homebrew/lib/python3.10/site-packages/giza/cmdline.py", line 19, in <module>
    from giza.config.runtime import RuntimeStateConfig
  File "/opt/homebrew/lib/python3.10/site-packages/giza/config/runtime.py", line 25, in <module>
    from giza.config.sphinx_config import available_sphinx_builders
  File "/opt/homebrew/lib/python3.10/site-packages/giza/config/sphinx_config.py", line 20, in <module>
    import sphinx.make_mode
ModuleNotFoundError: No module named 'sphinx.make_mode'

[jmikola]

Two small suggestions but I can confirm this builds locally (no new warnings):

$ ./rebuild.sh 
ERROR:giza.content.intersphinx:Error downloading https://docs.mongodb.com/manual/objects.inv: Got 308
/home/jmikola/.local/lib/python2.7/site-packages/giza/config/runtime.py:304: YAMLLoadWarning: calling yaml.load() without Loader=... is deprecated, as the default Loader is unsafe. Please read https://msg.pyyaml.org/load for full details.
  self._branch_conf = yaml.load(f)
source/reference/bson.txt:16: WARNING: term not in glossary: json
WARNING: logo file '.static/logo-mongodb.png' does not exist

And if you're curious what my rebuild.sh script does:

#!/bin/sh

rm -r build/master
rsync -a --delete ../phplib/docs/ source/
giza -l warning make publish

After that, I can view the output locally by pointing a web server to the build/master/html directory:

$ cat serve.sh 
#!/bin/sh
php -S localhost:8080 -t ./build/master/html/

[jmikola]

Let's also add /tutorial/connecting to the toctree in tutorial.txt to ensure this page is surfaced there as well.

Tutorials
=========

.. default-domain:: mongodb

.. toctree::

+  /tutorial/connecting
   /tutorial/crud
   /tutorial/collation