Add redeployment doc

[gtrkiller]

Applicable spec:

Overview

Add a new document to specify redeployment requirements.

Rationale

There exists a need to clarify and standardize what to do in a redeployment situation.

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 - 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)

[yanksyoon]

A small suggestion, thank you!

[github-actions]

Test coverage for d9123f7

Name                 Stmts   Miss Branch BrPart  Cover   Missing
----------------------------------------------------------------
src/charm.py           186     11     39      8    92%   145-146, 166-167, 186, 226-228, 242->254, 326->329, 351, 364, 373->376, 451
src/file_reader.py      17      0      6      0   100%
----------------------------------------------------------------
TOTAL                  203     11     45      8    92%

Static code analysis report

Run started:2024-04-30 15:26:22.680481

Test results:
  No issues identified.

Code scanned:
  Total lines of code: 1251
  Total lines skipped (#nosec): 1
  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):