chore: sections use .txt extension

index.bs

@@ -67,69 +67,69 @@ spec:infra; type:dfn; text:code point
 </pre>
 
 <pre class="include">
-path: sections/introduction.include
+path: sections/introduction.txt
 </pre>
 
 <pre class="include">
-path: sections/conventions.include
+path: sections/conventions.txt
 </pre>
 
 <!-- Section 3: Architecture =============================================== -->
 <pre class="include">
-path: sections/architecture.include
+path: sections/architecture.txt
 </pre>
 
 <!-- Section 4: Basic Event Interfaces ===================================== -->
 <pre class="include">
-path: sections/event-interfaces.include
+path: sections/event-interfaces.txt
 </pre>
 
 <!-- Section 5: The Events ================================================= -->
 <pre class="include">
-path: sections/event-types.include
+path: sections/event-types.txt
 </pre>
 
 <!-- Section 6: Keyboard and key values ==================================== -->
 <pre class="include">
-path: sections/keyboard.include
+path: sections/keyboard.txt
 </pre>
 
 <!-- Appendix A: Legacy Event Initializers ================================= -->
 <pre class="include">
-path: sections/legacy-event-initializers.include
+path: sections/legacy-event-initializers.txt
 </pre>
 
 <!-- Appendix B: Legacy Key Attributes ===================================== -->
 <pre class="include">
-path: sections/legacy-key-attributes.include
+path: sections/legacy-key-attributes.txt
 </pre>
 
 <!-- Appendix C: Legacy Event Types ======================================== -->
 <pre class="include">
-path: sections/legacy-event-types.include
+path: sections/legacy-event-types.txt
 </pre>
 
 <!-- Appendix D: Extending Events ========================================== -->
 <pre class="include">
-path: sections/extending-events.include
+path: sections/extending-events.txt
 </pre>
 
 <!-- Appendix E: Security Considerations =================================== -->
 <pre class="include">
-path: sections/security.include
+path: sections/security.txt
 </pre>
 
 <!-- Appendix F: Changes =================================================== -->
 <pre class="include">
-path: sections/changes.include
+path: sections/changes.txt
 </pre>
 
 <!-- Appendix G: Acknowledgements ========================================== -->
 <pre class="include">
-path: sections/acknowledgements.include
+path: sections/acknowledgements.txt
 </pre>
 
 <!-- Appendix H: Glossary  ================================================= -->
 <pre class="include">
-path: sections/glossary.include
+path: sections/glossary.txt
 </pre>