Document plot handlers.

[pfebrer]

Methods like Hamiltonian.plot.pdos() are not documented anywhere, and the only way of getting information about them is if your editor can show you the arguments and documentation of the function.

I want to document them, but I don't know how exactly. I have thought of modifying the class template for autosummary (https://github.com/zerothi/sisl/blame/main/docs/_templates/autosummary/class.rst) to check for the plot attribute and then add some documentation, but I don't know exactly how or if this is the best approach.

[pfebrer]

I don't know if it is possible to make sphinx document things like plot.pdos as a normal method of the Hamiltonian. I think this could be a reasonable approach.

Another idea that I have is to gather all plot handlers and create a page in the sisl.viz documentation like:

List of objects that can be used to generate each plot:

AtomicMatrixPlot
================
  - SparseCSR
  - SparseOrbital
  - SparseAtom
  - Hamiltonian

GeometryPlot
================
  - Geometry
  - fdfSileSiesta
  - pdosSileSiesta
  - tbtncSileTBtrans
  - cubeSile
  - pdbSile
  - xsfSile
  - xyzSile
  - asciiSileBigDFT
  - inSileFHIaims
  - gotSileGULP
  - hamiltonianSile
  - mdSileOpenMX
  - omxSileOpenMX
  - txtSileORCA
  - refSileScaleUp
  - restartSileScaleUp
  - aniSileSiesta
  - tshsSileSiesta
  - onlysSileSiesta
  - hsxSileSiesta
  - ncSileSiesta
  - structSileSiesta
  - xvSileSiesta
  - stdoutSileSiesta
  - deltancSileTBtrans
  - tbtavncSileTBtrans
  - phtncSilePHtrans
  - phtavncSilePHtrans
  - tbtprojncSileTBtrans
  - phtprojncSilePHtrans
  - tbtsencSileTBtrans
  - phtsencSilePHtrans
  - carSileVASP
  - chgSileVASP
  - locpotSileVASP
  - winSileWannier90
  - tbSileWannier90
  - centresSileWannier90

GridPlot
================
  - Grid
  - fdfSileSiesta
  - cubeSile
  - ncSileSiesta
  - chgSileVASP
  - locpotSileVASP
  - rhoSileSiesta
  - ldosSileSiesta
  - rhoinitSileSiesta
  - rhoxcSileSiesta
  - drhoSileSiesta
  - baderSileSiesta
  - iorhoSileSiesta
  - totalrhoSileSiesta
  - stsSileSiesta
  - stmldosSileSiesta
  - hartreeSileSiesta
  - neutralatomhartreeSileSiesta
  - totalhartreeSileSiesta
  - gridncSileSiesta
  - tsvncSileSiesta

SitesPlot
================
  - BrillouinZone

BandsPlot
================
  - BrillouinZone
  - Path
  - fdfSileSiesta
  - wfsxSileSiesta
  - BandsData
  - Dataset
  - DataArray
  - bandsSileSiesta
  - Aiida_node

FatbandsPlot
================
  - BrillouinZone
  - wfsxSileSiesta
  - BandsData

PdosPlot
================
  - PDOSData
  - Path
  - fdfSileSiesta
  - pdosSileSiesta
  - tbtncSileTBtrans
  - Hamiltonian
  - wfsxSileSiesta
  - tbtavncSileTBtrans
  - phtncSilePHtrans
  - phtavncSilePHtrans
  - tbtprojncSileTBtrans
  - phtprojncSilePHtrans

WavefunctionPlot
================
  - Path
  - fdfSileSiesta
  - Hamiltonian
  - wfsxSileSiesta
  - EigenstateData
  - EigenstateElectron

with links to the corresponding methods.

This information could also be at the beggining of the showcase notebooks.