QPR-12015 update manual for posix (include QL_ENABLE_SESSIONS)

Author: Eric Ehlers

tutorials.04.build_posix.md

@@ -57,7 +57,7 @@ and, when running cmake, you can omit flag `-DORE_USE_ZLIB=ON`.
     export BOOST_INCLUDEDIR=$DEMO_BOOST_INC
     export BOOST_LIBRARYDIR=$DEMO_BOOST_LIB
     export ZLIB_ROOT=%DEMO_ZLIB_ROOT%
-    cmake .. -DCMAKE_POSITION_INDEPENDENT_CODE=ON -DORE_BUILD_DOC=OFF -DORE_BUILD_EXAMPLES=OFF -DORE_BUILD_TESTS=OFF -DORE_BUILD_APP=OFF -DQL_BUILD_BENCHMARK=OFF -DQL_BUILD_EXAMPLES=OFF -DQL_BUILD_TEST_SUITE=OFF -DBoost_NO_WARN_NEW_VERSIONS=1 -DBoost_NO_SYSTEM_PATHS=1 -DORE_USE_ZLIB=ON -DQL_ENABLE_SESSIONS
+    cmake .. -DCMAKE_POSITION_INDEPENDENT_CODE=ON -DORE_BUILD_DOC=OFF -DORE_BUILD_EXAMPLES=OFF -DORE_BUILD_TESTS=OFF -DORE_BUILD_APP=OFF -DQL_BUILD_BENCHMARK=OFF -DQL_BUILD_EXAMPLES=OFF -DQL_BUILD_TEST_SUITE=OFF -DBoost_NO_WARN_NEW_VERSIONS=1 -DBoost_NO_SYSTEM_PATHS=1 -DORE_USE_ZLIB=ON -DQL_ENABLE_SESSIONS=ON
 
 ## Build ORE