Add docstring for Variant

src/Variant.jl

@@ -1,5 +1,22 @@
-# Edits are applied sequentially from first to last pos.
+"""
-# The vector must always be sorted by pos.
+    Variant{S<:BioSequence,T<:BioSymbol}
+
+A set of variations within a given sequence that are all found together. Depending on the
+field, it might also be referred to as a "genotype," "haplotype," or "strain."
+
+# Constructors
+
+    Variant(ref::S, edits::Vector{Edit{S,T}}) where {S<:BioSequence,T<:BioSymbol}
+    Variant(ref::S, vars::Vector{Variation{S,T}}) where {S<:BioSequence,T<:BioSymbol}
+    Variant(
+        aln::PairwiseAlignment{T,T}
+    ) where {T<:LongSequence{<:Union{BS.AminoAcidAlphabet,BS.NucleicAcidAlphabet}}}
+
+When constructing a `Variant` from a vector of [`Edit`](@ref)s or [`Variation`](@ref)s, the
+edits are applied sequentially from first to last position, therefore the vector must always
+be sorted by position. These edits are sorted automatically if constructing from an
+alignment.
+"""
 struct Variant{S<:BioSequence,T<:BioSymbol}
     ref::S
     edits::Vector{Edit{S,T}}