Wrong dir and code snippet bug in spelling and code style

[jorgepiloto]

In this section of the guide there are two bugs:

• The first code snippet points to a instead of a generic folder.
• The second code snippet does not properly render due to three dots in ... code:: instead of .. code::.

And here is the code: https://github.com/pyansys/dev-guide/blame/main/doc/source/guidelines/dev_practices.rst#L121-L137