BetterHelp

The doc command will display help written for custom functions in the Help Browser. However, the allowed markup is rather limited. According to the official documentation, http://www.mathworks.com/help/matlab/matlab_prog/add-help-for-your-program.html, the only thing you can add is a See Also section. Matlab will also recognize a Note section (and a few others) and will highlight the function name if it is in all caps (or mixed case, if the actual function name is mixed case).

This function provides a modified copy of the undocumented help2html.m function, as well as a few other files to enable slightly more markup functionality, making use of the limited html capabilities of the default help browser.
New features include:
Additional custom sections
3 text styles - regular, bold, and code
Definition style lists
Doesn't affect files without %CUSTOM_HELP% tag, so other people's formatting is unaffected.
Style customization using css (by editing helpwin.css)

For BetterHelp to work, the BetterHelp directory containing help2html.m, +myHelpUtils/, and private/ must be on the path. To go back to normal, just delete constructed files or remove the directory from the path.

MathWorks changed the help generation slightly in R2012b, so use BetterHelp2012b if you are running R2012b+, instead of BetterHelp.