doc: we do not need gcc-c++.i686 on fedora

This package is not needed for building on fedora and currently causes
dependency issue with the fedora package manager, so remove it.

Fixes zephyrproject-rtos#6013

Signed-off-by: Anas Nashif <anas.nashif@intel.com>

doc/getting_started/installation_linux.rst

@@ -65,8 +65,7 @@ Install the required packages in a Fedora host system with:
    sudo dnf install git cmake ninja-build gperf ccache\
 	 doxygen dfu-util dtc python3-pip \
 	 python3-ply python3-yaml dfu-util dtc python3-pykwalify \
-         glibc-devel.i686 libstdc++-devel.i686 autoconf automake libtool \
-         gcc-c++.i686
+         glibc-devel.i686 libstdc++-devel.i686 autoconf automake libtool
 
 Install additional packages required for development with Zephyr::