docs: add kb on spire office truncated text issue

[petar-i-todorov]

Part of https://github.com/telerik/reporting/issues/5529.

[Copilot]

Pull Request Overview

This PR adds a knowledge base article documenting a text truncation issue that occurs when using Telerik Reporting alongside Spire.Office libraries.

• Documents the root cause of text truncation in Telerik reports when Spire.Office modifies global StringFormat state
• Provides a code solution to manually remove the problematic MeasureTrailingSpaces flag
• Includes environment details and version information for affected components

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