GH-426 - Remove notes on mandel dev install.

Mandel dev install is no longer the recommendation.

For users utilizing native contract unit testing, make install no longer installs the required header and libraries. It's recommended to utilize the headers and libraries directly from mandel's build directory, or to use the mandel-dev package. Installation of these headers and libraries can still be performed with a make dev-install if absolutely needed.

README.md

@@ -64,20 +64,6 @@ We support the following CMake options:
 
 I highly recommend the ccache options. They don't speed up the first clean build, but they speed up future clean builds after the first build.
 
-### Installing mandel dev for use with mandel.cdt (or others)
-
-The following instructions will install mandel and the development packages.  Installing is not strictly necessary. Instructions are provided, for example, in `mandel.cdt` for development and testing against a `mandel` source build directory (which may be preferable).
-
-**Warning:** It is highly recommended to select a `CMAKE_INSTALL_PREFIX` location different than the default `/usr/local`.  Here, `$HOME/mandeldev` is used as an example that should be safe for most dev systems, but each developer should determine if another location is better suited to their specific needs.
-
-```
-git submodule update --init --recursive
-mkdir build
-cd build
-cmake -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_INSTALL_PREFIX=$HOME/mandeldev ..
-make -j $(nproc) dev-install
-```
-
 ### Running tests
 
 ```