Add supporting themes required for Lotusdocs

themes/twbs/bootstrap/SECURITY.md

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+# Reporting Security Issues
+
+The Bootstrap team and community take security issues in Bootstrap seriously. We appreciate your efforts to responsibly disclose your findings, and will make every effort to acknowledge your contributions.
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+To report a security issue, email [security@getbootstrap.com](mailto:security@getbootstrap.com) and include the word "SECURITY" in the subject line.
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+We'll endeavor to respond quickly, and will keep you updated throughout the process.