docs: update docs and add test cases

src/NetMSA.jl

@@ -8,9 +8,9 @@ using StatsBase
 
 export createPeerMatrix, matrixalignment
 
-"""
-Store the position of a given particle. Position ``x_s_i (r)`` of the particle
-``p_s_i`` is defined by using the row ``r`` that contains the symbol ``s_i`` as
+@doc raw"""
+Store the position of a given particle. Position ``x_{s_{i}}(r)`` of the particle
+``p_{s_{i}}`` is defined by using the row ``r`` that contains the symbol ``s_i`` as
 well as locations of the symbol ``s_i`` in the different columns (indexes of the
 columns that contain ``s_i`` ) in the row ``r``.
 """