Fix typo in sanic-ext configuration readme.md file

[jakkaz]

Spotted a small typo while browsing docs.
Fixing "configurtaion" to "configuration".

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.066%. Comparing base (12e61db) to head (a84fbec).
Report is 1 commits behind head on main.

❗ Current head a84fbec differs from pull request most recent head d9c283a. Consider uploading reports for the commit d9c283a to get more accurate results

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #2930       +/-   ##
=============================================
+ Coverage   87.999%   88.066%   +0.067%     
=============================================
  Files           94        94               
  Lines         7408      7433       +25     
  Branches      1307      1283       -24     
=============================================
+ Hits          6519      6546       +27     
- Misses         598       620       +22     
+ Partials       291       267       -24     

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