update installation docs with info about compiler version

docs/INSTALLATION.md

@@ -16,7 +16,11 @@ Then, run `yum install quarkdb quarkdb-debuginfo`, and you're done.
 
 ## Building from source
 
-Check out `utils/el7-packages.sh` for a list of build dependencies.
+### Requirements/ Dependencies
+  * Check out `utils/el7-packages.sh` for a list of build dependencies.
+  * Build will fail with older versions of gcc/gcc-c++
+    * On CC7, run `yum install centos-release-sc && yum install devtoolset-6 && source /opt/rh/devtoolset-6/enable`
+
 The following will compile QuarkDB and run the tests.
 
 ```