Greek keymap contribution

Attached you can find the .txt file with the keymap for the greek keyboard - us-latin layout.
[el_GR.txt](https://github.com/kernc/logkeys/files/1740192/el_GR.txt)
Greek letters are not implemented. Transliteration can be used like this:
a -> Alpha (α)
b -> Beta (β)
g -> Gamma (γ)
d -> Delta (δ)
e -> Epsilon (ε)
z -> Zeta (ζ)
h -> Eta (η)
u -> Theta (θ)
i -> Iota (ι)
k -> Kappa (κ)
l -> Lambda (λ)
m -> Mu (μ)
n -> Nu (ν)
j -> Xi (ξ)
o -> Omicron (ο)
p -> Pi (π)
r -> Rho (ρ)
s -> Sigma (σ)
w -> Sigma teliko (ς)
t -> Tau (τ)
y -> Upsion (υ)
f -> Phi (φ)
x -> Chi (χ)
c -> Psi (ψ)
v -> Omega (ω)

Start by reviewing the attached el_GR.txt file and comparing its Greek transliteration mappings with the repository's existing keymap organization. Trace how keymap files are discovered or selected, then verify that the Greek layout is available and produces the listed mappings.

Written by the indexing model from the issue text.