Clean README, docs and docstrings

Co-Authored-By: Claudio Moroni <43729990+ClaudMor@users.noreply.github.com>
Co-Authored-By: Pietro Monticone <38562595+pitmonticone@users.noreply.github.com>

Author: 3 people

README.md

@@ -27,13 +27,12 @@ Press `]` in the Julia REPL and then
 ```julia
 pkg> add https://github.com/InPhyT/MultilayerGraphs.jl
 ```
-[Registration](https://github.com/JuliaRegistries/General/pull/66311) is under way.
 
 [Registration](https://github.com/JuliaRegistries/General/pull/66311) is in progress.
 
 ## Tutorial
 
-In the package documentation we have written a [tutorial](https://inphyt.github.io/MultilayerGraphs.jl/stable/#Tutorial) to illustrate how to define, handle and analyse a [`MultilayerGraph`](@ref) (the directed version is completely analogous).
+In the package documentation we have prepared a [tutorial](https://inphyt.github.io/MultilayerGraphs.jl/stable/#Tutorial) to illustrate how to define, handle and analyse a [`MultilayerGraph`](@ref) (the directed version is completely analogous).
 
 ## Future Developments
 
@@ -54,12 +53,14 @@ Here we highlight the major future developments we have currently identified:
 
 ## How to Contribute
 
-If you wish to change or add some functionality, please file an [issue](https://github.com/InPhyT/MultilayerGraphs.jl/issues).
+The package is currently under development and further steps would benefit enormously from the precious feedback of the [JuliaGraph people](https://github.com/orgs/JuliaGraphs/people), graph theorists, network scientists and all the users who might have general questions or suggestions. 
+
+Therefore feel free to open [discussions](https://github.com/InPhyT/MultilayerGraphs.jl/discussions), [issues](https://github.com/InPhyT/MultilayerGraphs.jl/issues) or [PRs](https://github.com/InPhyT/MultilayerGraphs.jl/pulls). They are very welcome!   
 
 ## How to Cite
 
 If you use this package in your work, please cite this repository using the metadata in [`CITATION.bib`](https://github.com/InPhyT/MultilayerGraphs.jl/blob/main/CITATION.bib).
 
 ## References
 
-De Domenico et al. (2013) [Mathematical Formulation of Multilayer Networks](https://doi.org/10.1103/PhysRevX.3.041022). *Physical Review X*
+De Domenico et al. (2013) [Mathematical Formulation of Multilayer Networks](https://doi.org/10.1103/PhysRevX.3.041022). *Physical Review X*.

docs/src/index.md

@@ -31,6 +31,7 @@ Press `]` in the Julia REPL and then
 ```julia
 pkg> add https://github.com/InPhyT/MultilayerGraphs.jl
 ```
+
 [Registration](https://github.com/JuliaRegistries/General/pull/66311) is in progress.
 
 ## Tutorial
@@ -520,12 +521,14 @@ Other extended functions are: [`is_directed`](@ref), [`has_vertex`](@ref), [`ne`
 
 ## How to Contribute
 
-If you wish to change or add some functionality, please file an [issue](https://github.com/InPhyT/MultilayerGraphs.jl/issues).
+The package is currently under development and further steps would benefit enormously from the precious feedback of the [JuliaGraph people](https://github.com/orgs/JuliaGraphs/people), graph theorists, network scientists and all the users who might have general questions or suggestions. 
+
+Therefore feel free to open [discussions](https://github.com/InPhyT/MultilayerGraphs.jl/discussions), [issues](https://github.com/InPhyT/MultilayerGraphs.jl/issues) or [PRs](https://github.com/InPhyT/MultilayerGraphs.jl/pulls). They are very welcome!   
 
 ## How to Cite
 
 If you use this package in your work, please cite this repository using the metadata in [`CITATION.bib`](https://github.com/InPhyT/MultilayerGraphs.jl/blob/main/CITATION.bib).
 
 ## References
 
-De Domenico et al. (2013) [Mathematical Formulation of Multilayer Networks](https://doi.org/10.1103/PhysRevX.3.041022). *Physical Review X*
+De Domenico et al. (2013) [Mathematical Formulation of Multilayer Networks](https://doi.org/10.1103/PhysRevX.3.041022). *Physical Review X*.

src/abstractmultilayergraph.jl

@@ -375,14 +375,44 @@ Return the nodes of the AbstractMultilayerGraph `mg`.
 nodes(mg::M) where {M <: AbstractMultilayerGraph} = [vertex.node for vertex in  vertices(mg.layers[(1,1)])]
 
 # Graphs.jl's internals extra overrides
+"""
+    indegree(mg::M, v::V) where {T, M <: AbstractMultilayerGraph{T, <: Real}, V <: MultilayerVertex{T}}
+
+Get the indegree of vertex `v` in `mg`.
+"""
 Graphs.indegree(mg::M, v::V) where {T, M <: AbstractMultilayerGraph{T, <: Real}, V <: MultilayerVertex{T}} = length(inneighbors(mg, v))
+"""
+    indegree(mg::M, vs::AbstractVector{V} = vertices(mg)) where {T,M <: AbstractMultilayerGraph{T, <: Real}, V <: MultilayerVertex{T}} 
+
+Get the vector of indegrees of vertices `vs` in `mg`.
+"""
 Graphs.indegree(mg::M, vs::AbstractVector{V} = vertices(mg)) where {T,M <: AbstractMultilayerGraph{T, <: Real}, V <: MultilayerVertex{T}} = [indegree(mg, x) for x in vs]
 
+"""
+    outdegree(mg::M, v::V) where {T, M <: AbstractMultilayerGraph{T, <: Real}, V <: MultilayerVertex{T}}
+
+Get the outdegree of vertex `v` in `mg`.
+"""
 Graphs.outdegree(mg::M, v::V) where {T, M <: AbstractMultilayerGraph{T, <: Real}, V <: MultilayerVertex{T}} = length(outneighbors(mg, v))
+"""
+outdegree(mg::M, vs::AbstractVector{V} = vertices(mg)) where {T,M <: AbstractMultilayerGraph{T, <: Real}, V <: MultilayerVertex{T}} 
+
+Get the vector of outdegrees of vertices `vs` in `mg`.
+"""
 Graphs.outdegree(mg::M, vs::AbstractVector{V} = vertices(mg)) where {T, M <: AbstractMultilayerGraph{T, <: Real}, V <: MultilayerVertex{T}} = [outdegree(mg, x) for x in vs]
 
+"""
+    degree(mg::M, v::V) where {T, M <: AbstractMultilayerGraph{T, <: Real}, V <: MultilayerVertex{T}}
+
+Get the degree of vertices `vs` in `mg`.
+"""
 Graphs.degree(mg::M, vs::AbstractVector{V} = vertices(mg)) where {T, M <: AbstractMultilayerGraph{T, <: Real}, V <: MultilayerVertex{T}}  = [degree(mg, x) for x in vs]
 
+"""
+    neighbors(mg::M, v::V) where {T, M <: AbstractMultilayerGraph{T, <: Real}, V <: MultilayerVertex{T}}
+
+Get the neighbors of vertices `vs` in `mg`. Reduces to `outneighbors` for both directed and undirected multilayer graphs.
+"""
 Graphs.neighbors(mg::M, v::V) where {T, M <: AbstractMultilayerGraph{T, <: Real}, V <: MultilayerVertex{T}}   = outneighbors(mg, v)
 
 """