SNOW-1337069 connection pool doc fix

[sfc-gh-knozderko]

Description

SNOW-1337069 Fix note about special signs in connection string

Checklist

• [x] Code compiles correctly
• [x] Code is formatted according to Coding Conventions
• [x] Created tests which fail without the change (if possible)
• [x] All tests passing (dotnet test)
• [x] Extended the README / documentation, if necessary
• [x] Provide JIRA issue id (if possible) or GitHub issue id in PR name

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 85.31%. Comparing base (921b9df) to head (c7f4575).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## pool/SNOW-860872-connection-pool #958 +/- ## ==================================================================== - Coverage 85.56% 85.31% -0.25% ==================================================================== Files 106 106 Lines 10742 10742 Branches 1027 1027 ==================================================================== - Hits 9191 9165 -26 - Misses 1302 1329 +27 + Partials 249 248 -1 ```

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