Bugfix/typos

[jamie-taylor-rjj]

Rationale for this PR

This PR fixes a number of typos in the generated values for both the X-Permitted-Cross-Domains and X-Frame-Options headers.

PR Checklist

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Essential

These items are essential and must be completed for each commit. If they are not completed, the PR may not be accepted.

• [ ❓ ] I have added tests to the OwaspHeaders.Core.Tests project
• [ ❓ ] I have run the dotnet-format command and fixed any .editorconfig issues
• [ ❓ ] I have ensured that the code coverage has not dropped below 65%
• [ ❓ ] I have increased the version number in OwaspHeaders.Core.csproj (only relevant for code changes)

Optional

• [ ❓ ] I have documented the new feature in the docs directory
• [ ❓ ] I have provided a code sample, showing how someone could use the new code

Any Other Information

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