Manual:$wgTidyConfig

Details
Configuration for HTML postprocessing tool. Set this to a configuration array to enable an external tool. Dave Raggett's "HTML Tidy" is typically used. See http://www.w3.org/People/Raggett/tidy/

If this is null and $wgUseTidy is true, the deprecated configuration parameters will be used instead. If this is null and $wgUseTidy is false, a pure PHP fallback will be used.

Keys are:
 * driver: May be:
 * RaggettInternalHHVM: Use the limited-functionality HHVM extension
 * RaggettInternalPHP: Use the PECL extension
 * RaggettExternal: Shell out to an external binary (tidyBin)
 * tidyConfigFile: Path to configuration file for any of the Raggett drivers
 * debugComment: True to add a comment to the output with warning messages
 * tidyBin: For RaggettExternal, the path to the tidy binary.
 * tidyCommandLine: For RaggettExternal, additional command line options.