chore(docs): Update tutorial

[alithethird]

Overview

Standarise the Discourse tutorial with other tutorials and improve/fix the tutorial.

Rationale

Juju Events Changes

Module Changes

Library Changes

Checklist

• [x] The charm style guide was applied
• [x] The contributing guide was applied
• [x] The changes are compliant with ISD054 - Manging Charm Complexity
• [x] The documentation is generated using src-docs
• [x] The documentation for charmhub is updated.
• [x] The PR is tagged with appropriate label (urgent, trivial, complex)

[github-actions[bot]]

Test coverage for c59afb0af9d11fb8d58c0ee222b59d4adcb7cd2f

Name              Stmts   Miss Branch BrPart  Cover   Missing
-------------------------------------------------------------
src/charm.py        373     41     94     15    88%   184, 192-193, 205, 337->345, 378->383, 395, 583-585, 590-591, 603-605, 610-611, 623-625, 648-650, 692->exit, 702->exit, 751-754, 764-765, 789-790, 802-803, 830-832, 834->839, 836-837, 879-880, 896-897, 907->exit, 921
src/database.py      29      1      8      1    95%   56
-------------------------------------------------------------
TOTAL               402     42    102     16    88%

Static code analysis report

Run started:2024-10-07 13:07:06.598996

Test results:
    No issues identified.

Code scanned:
    Total lines of code: 2458
    Total lines skipped (#nosec): 2
    Total potential issues skipped due to specifically being disabled (e.g., #nosec BXXX): 0

Run metrics:
    Total issues (by severity):
        Undefined: 0
        Low: 0
        Medium: 0
        High: 0
    Total issues (by confidence):
        Undefined: 0
        Low: 0
        Medium: 0
        High: 0
Files skipped (0):