rnndb/graph: add Maxwell 2 texture headers documentation
rnndb/graph: add Maxwell 2 texture headers documentation

GM1 introduced a new texture format that is being enforced for GM2 and
above. Document this format.

envytools/envytools,karolherbst/envytools,MoochMcGee/envytools,grate-driver/envytools,grate-driver/envytools,pierremoreau/envytools,pierremoreau/envytools,envytools/envytools,MoochMcGee/envytools,karolherbst/envytools,hakzsam/envytools,karolherbst/envytools,MoochMcGee/envytools,pierremoreau/envytools,grate-driver/envytools,envytools/envytools,karolherbst/envytools,hakzsam/envytools,grate-driver/envytools,hakzsam/envytools,envytools/envytools,grate-driver/envytools,karolherbst/envytools,pierremoreau/envytools,envytools/envytools,MoochMcGee/envytools,pierremoreau/envytools,hakzsam/envytools,MoochMcGee/envytools,hakzsam/envytools