How to make an introduction page with Doxygen

Have a look at the mainpage command.

Also, have a look this answer to another thread: How to include custom files in Doxygen. It states that there are three extensions which doxygen classes as additional documentation files: .dox, .txt and .doc. Files with these extensions do not appear in the file index but can be used to include additional information into your final documentation - very useful for documentation that is necessary but that is not really appropriate to include with your source code (for example, an FAQ)

So I would recommend having a mainpage.dox (or similarly named) file in your project directory to introduce you SDK. Note that inside this file you need to put one or more C/C++ style comment blocks.

Note that with Doxygen release 1.8.0 you can also add Markdown formated pages. For this to work you need to create pages with a .md or .markdown extension, and add the following to the config file:

INPUT += your_page.md
FILE_PATTERNS += *.md *.markdown

See http://www.doxygen.nl/manual/markdown.html#md_page_header for details.

As of v1.8.8 there is also the option USE_MDFILE_AS_MAINPAGE. So make sure to add your index file, e.g. README.md, to INPUT and set it as this option's value:

INPUT += README.md
USE_MDFILE_AS_MAINPAGE = README.md