Add target/ dir in .gitignore

emu/examples/multiply_by_scalar/target/.rustc_info.json

    
           {"rustc_fingerprint":15037809574512656097,"outputs":{"1617349019360157463":["___\nlib___.rlib\nlib___.so\nlib___.so\nlib___.a\nlib___.so\n/home/calebwin/.rustup/toolchains/stable-x86_64-unknown-linux-gnu\ndebug_assertions\nproc_macro\ntarget_arch=\"x86_64\"\ntarget_endian=\"little\"\ntarget_env=\"gnu\"\ntarget_family=\"unix\"\ntarget_feature=\"fxsr\"\ntarget_feature=\"sse\"\ntarget_feature=\"sse2\"\ntarget_os=\"linux\"\ntarget_pointer_width=\"64\"\ntarget_vendor=\"unknown\"\nunix\n",""],"15337506775154344876":["___\nlib___.rlib\nlib___.so\nlib___.so\nlib___.a\nlib___.so\n/home/calebwin/.rustup/toolchains/stable-x86_64-unknown-linux-gnu\ndebug_assertions\nproc_macro\ntarget_arch=\"x86_64\"\ntarget_endian=\"little\"\ntarget_env=\"gnu\"\ntarget_family=\"unix\"\ntarget_feature=\"fxsr\"\ntarget_feature=\"sse\"\ntarget_feature=\"sse2\"\ntarget_os=\"linux\"\ntarget_pointer_width=\"64\"\ntarget_vendor=\"unknown\"\nunix\n",""],"1164083562126845933":["rustc 1.33.0 (2aa4c46cf 2019-02-28)\nbinary: rustc\ncommit-hash: 2aa4c46cfdd726e97360c2734835aa3515e8c858\ncommit-date: 2019-02-28\nhost: x86_64-unknown-linux-gnu\nrelease: 1.33.0\nLLVM version: 8.0\n",""]},"successes":{}}

You don't need to store examples/multiply_by_scalar/target

Thanks @maccam912 for the fix.