Added readme to base of mercurial repository.

README.txt

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+
+
+If you are reading this file then you must have downloaded dlib via the 
+mercurial repository.  If you are new to dlib then go read the introduction
+and how to compile pages at http://dlib.net/intro.html and http://dlib.net/compile.html.
+If you are planning on contributing code then also read the contribution
+instructions at http://dlib.net/howto_contribute.html.
+
+
+COMPILING DLIB EXAMPLE PROGRAMS
+   go into the examples folder and type:
+   mkdir build; cd build; cmake .. ; cmake --build .
+
+   That will build all the examples.  Note that there is nothing to install
+   when using dlib.  It's just a folder of source files.  Sometimes people
+   tell me dlib should be compiled and installed as some kind of shared
+   library, however, they are wrong. Please read this http://dlib.net/howto_contribute.html#9 
+   before starting this argument again.  
+
+
+RUNNING THE UNIT TEST SUITE
+   Type the following to compile and run the dlib unit test suite (it takes a while):
+   cd dlib/test; mkdir build; cd build; cmake ..; cmake --build . --config Release; ./test --runall
+
+   Note that on windows your compiler might put the test executable in a subfolder called
+   Release.  If that's the case then you have to go to that folder before running the test.
+
+
+DOCUMENTATION
+   The mercurial repository doesn't contain finished documentation.  The stuff in
+   the docs folder is just a bunch of scripts and xml files used to generate the 
+   documentation.  There is a readme in docs/README.txt which discusses how to do
+   this.  However, unless you are trying to modify the documentation, you should
+   just download a copy from http://dlib.net.  That would probably be easier than
+   setting up your environment to generate the documentation yourself.