Update Integration Tests build directions.

README.md

@@ -40,6 +40,10 @@ If issues persist with ccache
 export CCACHE_DISABLE=1
 ```
 
+### Building Integration Tests
+
+Integration tests require access to a mandel build.  Instructions below provide additional steps for using a mandel built from source or installed.  For development purposes it is generally advised to use mandel built from source instead of installed.
+
 #### For building integration tests with mandel built from source (not installed)
 
 Need to provide some environment variables to find necessary test dependencies
@@ -50,6 +54,16 @@ export mandel_DIR=${mandel_root}/build/lib/cmake/eosio
 export eosio_DIR=${mandel_root}/build/lib/cmake/eosio
 ```
 
+#### For building integration tests with mandel dev install
+
+Need to provide direction on `PATH` to find necessary dev/test dependencies and mandel package.
+
+Update `PATH` to include the location mandel dev was installed to. Example from mandel dev install instructions uses `$HOME/mandeldev`, which will be used here as well.
+
+```sh
+export export PATH="$HOME/mandeldev:$PATH"
+```
+
 ### Guided Installation or Building from Scratch
 ```sh
 git clone --recursive https://github.com/eosnetworkfoundation/mandel.cdt