Modified input.md

[jonlym]

Hi Bharat,

I modified the input.md file with the following additions:

• table with an exhaustive list of YAML parameters
• examples of YAML file, units, ideal_gas, stoich_solid, interacting_interface, lateral_interaction
• added links to pMuTT, YAML validator, etc.
• added equations for NASA7, NASA9, Shomate, reaction kinetic parameters.

Could you check if:

• the YAML parameters table and equations render correctly when you regenerate the documentation
• I missed any YAML parameters
• if my interpretations of all the directives are correct
• other miscellaneous typos or inconsistencies?

[jonlym]

It looks like some minor things did not render properly, like G‡ and the code font in the YAML table. I'll fix those and make another pull request.