Rename function to Empirical Average

[sebgrijalva]

QuantumMeasurements.jl/src/tomography.jl

Line 66 in a6d29fb

function compute_expectation_value(meas::Vector{T}, observable::KronBlock) where {T<:DitStr}

For future use, this function seems to be calculating the empirical average given a series of measurements and a Pauli observable. We can generalize the use of these empirical averages and I believe it is clearer to rename compute_expectation_value() to this since it gives the impression that it calculates the true mean.