Update tutorial to reflect new create-user action

[mthaddon]

Overview

Trivial doc update for the tutorial to incorporate the new create-user action. I think changing the ordering a little to create the user before visiting the page makes sense too, as this will mean you get a "log in" prompt rather than a "register your first user" prompt.

Rationale

The action specified in the tutorial no longer exists, so update to include the new action.

Juju Events Changes

N/A

Module Changes

N/A

Library Changes

N/A

Checklist

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

[github-actions]

Test coverage for 69831f8

Name              Stmts   Miss Branch BrPart  Cover   Missing
-------------------------------------------------------------
src/charm.py        371     41     94     15    88%   184, 192-193, 205, 337->345, 378->383, 395, 577-579, 584-585, 597-599, 604-605, 617-619, 642-644, 686->exit, 696->exit, 745-748, 758-759, 783-784, 796-797, 824-826, 828->833, 830-831, 873-874, 890-891, 901->exit, 915
src/database.py      29      1      8      1    95%   56
-------------------------------------------------------------
TOTAL               400     42    102     16    88%

Static code analysis report

Run started:2024-06-17 12:15:44.421423

Test results:
  No issues identified.

Code scanned:
  Total lines of code: 2336
  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):

[erinecon]

LGTM