message: Updated doxyfile - added missing files
  Added missing Java/C#/Switft files - that fixes references to them. Removed non-existent "JavaCsharpUsage.md".
diff: @@ -753,7 +753,9 @@ INPUT = "FlatBuffers.md" \
  "CUsage.md" \
  "DartUsage.md" \
  "GoUsage.md" \
  - "JavaCsharpUsage.md" \
  + "JavaUsage.md" \
  + "CsharpUsage.md" \
  + "SwiftUsage.md" \
  "JavaScriptUsage.md" \
  "TypeScriptUsage.md" \
  "PHPUsage.md" \
  