README examples do not work one after the other.

on the readme
the first example and the second example do not compose
a new user would naturally try both and get frustrated

perhaps the example that nominally states `without MPI` has a uniprocessor
MPI under the hood causing interference?

but still this is frustrating as a user experience

```julia
julia> using LinearAlgebra, Elemental

julia> A = Elemental.Matrix(Float64)
0×0 Elemental.Matrix{Float64}

julia> using MPI, MPIClusterManagers, Distributed

julia> man = MPIManager(np = 4);
ERROR: AssertionError: MPI.Initialized() == mgr.launched
Stacktrace:
[1] MPIManager(; np::Int64, launch_timeout::Float64, mode::TransportMode, master_tcp_interface::String) at /Users/edelman/.julia/packages/MPIClusterManagers/0ZYYQ/src/mpimanager.jl:64
[2] top-level scope at REPL[4]:1
```