Documentation request for v2.3.0

[dyzheng]

I have several questions for using ABACUSv2.3.0:

• [x] 1. How can I calculate BSSE for molecular formation energy?
• [ ] 2. How can I calculate SOC effect?
• [x] 3. How can I print PDOS or PBANDS or wavefunction in real space?
• [ ] 4. How can I calculate DFT+U effect?
• [x] 5. How can I print Hamiltonian matrix in real space?
• [x] 6. How can I use FIRE method if I only want to do relax calculation?

[caic99]

@dyzheng SOC example @wenfei-li DFT+U Thanks!