docs: update backup file docs

[yanksyoon]

Applicable spec: N/A

Overview

Update backup guide to be copy-pasteable & fix some bugs with pathing.

Rationale

:)

Juju Events Changes

Module Changes

Library Changes

Checklist

• The charm style guide was applied
• The contributing guide was applied
• The changes are compliant with ISD054 - Managing 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)

[Thanhphan1147]

LGTM, thanks!

[yanksyoon]

Fixed issues w/ lint from the previous PR that I didn't catch locally after running tox -e unit.

[github-actions]

Test coverage for ccd13ec

Name                Stmts   Miss Branch BrPart  Cover   Missing
---------------------------------------------------------------
src/actions.py         30      0      4      0   100%
src/agent.py          123      0     20      0   100%
src/auth_proxy.py      53      0      8      0   100%
src/charm.py           89      0     14      0   100%
src/cos.py             21      0      0      0   100%
src/ingress.py         17      0      4      0   100%
src/jenkins.py        375      0     60      0   100%
src/pebble.py          25      0      2      0   100%
src/state.py          110      0     24      0   100%
src/timerange.py       31      0      6      0   100%
---------------------------------------------------------------
TOTAL                 874      0    142      0   100%

Static code analysis report

Run started:2024-04-30 09:27:44.660952

Test results:
  No issues identified.

Code scanned:
  Total lines of code: 7485
  Total lines skipped (#nosec): 6
  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):