Update README.md

README.md

@@ -22,7 +22,7 @@ Pkg.add("Backboner")
 
 The `Protein` type wraps a vector of `Chain`s, which in turn wraps the `Backbone{4}` type (4, because it stores the positions of 4 atoms per residue: N, CA, C, O). The `Backbone{N}` type has the `N` type parameter in order to remain flexible. It allows one pass only the N, CA, and C atoms of a backbone, such that the O atom positions can added in using the `add_oxygens` function.
 
-The package includes a `SecondaryStructure` type, which describes the secondary structure of a single residue in a chain. The secondary structure of an entire chain is described by a `Vector{Char}`, where '-' stands for coil/loop, 'H' for helix, and 'E' for strand. For assignment of secondary structure, this package uses the [AssigningSecondaryStructure.jl](https://github.com/MurrellGroup/AssigningSecondaryStructure.jl) package, which implements a simplified version of the DSSP algorithm to assign three types of secondary structure to residues: loop, helix, and strand.
+The secondary structure of an entire chain is described by a `Vector{Char}`, where '-' stands for coil/loop, 'H' for helix, and 'E' for strand. For assignment of secondary structure, this package uses the [AssigningSecondaryStructure.jl](https://github.com/MurrellGroup/AssigningSecondaryStructure.jl) package, which implements a simplified version of the DSSP algorithm.
 
 Protein backbones can be loaded from a PDB file using the `pdb_to_protein` function, which returns a `Protein` instance. Inversely, a `Protein` instance can be written to a PDB file using the `protein_to_pdb` function.