Add documentation for encrypt payload

[cr0hn]

Goal

Add doc for using sanic-jwt-payload-encrypt as plugin

Please, check english is ok

[codecov]

Codecov Report

Merging #189 (4efb756) into main (86f66e6) will increase coverage by 0.11%.
The diff coverage is n/a.

❗ Current head 4efb756 differs from pull request most recent head 2d7d3c0. Consider uploading reports for the commit 2d7d3c0 to get more accurate results

@@            Coverage Diff             @@
##             main     #189      +/-   ##
==========================================
+ Coverage   97.57%   97.68%   +0.11%     
==========================================
  Files          13       12       -1     
  Lines        1070     1038      -32     
  Branches      176      171       -5     
==========================================
- Hits         1044     1014      -30     
+ Misses         16       15       -1     
+ Partials       10        9       -1     

Impacted Files	Coverage Δ
sanic_jwt/authentication.py	93.75% <0.00%> (-0.12%)	⬇️
sanic_jwt/configuration.py	99.35% <0.00%> (-0.01%)	⬇️
sanic_jwt/endpoints.py	96.38% <0.00%> (ø)
sanic_jwt/responses.py	100.00% <0.00%> (ø)
sanic_jwt/decorators.py	96.69% <0.00%> (ø)
sanic_jwt/exceptions.py	100.00% <0.00%> (ø)
sanic_jwt/__init__.py
sanic_jwt/initialization.py	100.00% <0.00%> (+1.19%)	⬆️

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[ahopkins]

Looks good. I added a few modifications.

[cr0hn]

Oks for me