Change recommended output directory in build instruction

[dvrogozh]

Current build instruction starts with README.rst:

1. Get gmmlib repo, make it look like
   < workspace >
   |- GmmLib

2. $ mkdir /build

3. $ cd /build

4. cmake [-DCMAKE_BUILD_TYPE= Release | Debug | ReleaseInternal] [-DARCH= 64 | 32] ../GmmLib

5. $ make -j8 ( Also performs compile time ULT)

This will lead naive end-user to the issue if he will try to build few projects from intel: they all suggest to create build directory in the workspace:). As a result all projects will try to generate Mekefiles in the same folder and will eventually conflict.

Please:

1. Drop a talk about a "workspace" to be created - user should clone only the repository
2. Change the build instruction suggesting to create build directory inside the cloned copy. For example:

1. Get gmmlib sources and change to the root directory, for example:
git clone https://github.com/intel/gmmlib.git && cd gmmlib
2. Configure, build and install as follows:
mkdir build && cd build
cmake ..
make
make install

[drprajap]

The change has been pushed. 40b45bd.
Thanks.