Changes in 8037a45: add variables to help with memory management

				examples/alphafold2.md
			
          @@ -120,6 +120,14 @@ Memory is going to be an issue with larger protein sizes. The original publicati

           "The memory usage is approximately quadratic in the number of residues, so a 2,500 residue protein involves using unified memory so that we can greatly exceed the memory of a single V100. In our cloud setup, a single V100 is used for computation on a 2,500 residue protein but we requested four GPUs to have sufficient memory."

          +The following environment variable settings may help with larger polypeptide calculations (> 1,200 aa).

          +

          +```

          +TF_FORCE_UNIFIED_MEMORY=1

          +XLA_PYTHON_CLIENT_MEM_FRACTION=0.5

          +XLA_PYTHON_CLIENT_ALLOCATOR=platform

          +```

          +*Thanks Ci Ji Lim at Wisconsin for suggesting and testing these.*

           ### pTM scores

           The pTM scores are not calculated using the default model. To get pTM scored models you need to change the model names in the input. We have provided a template wrapper script (https://sbgrid.org//wiki/examples/alphafold2) which you can change to your requirements. To get pTM scores you will need to change the model_name line to "model_1_ptm,model_2_ptm" etc.

...	...	@@ -120,6 +120,14 @@ Memory is going to be an issue with larger protein sizes. The original publicati
120	120
121	121	"The memory usage is approximately quadratic in the number of residues, so a 2,500 residue protein involves using unified memory so that we can greatly exceed the memory of a single V100. In our cloud setup, a single V100 is used for computation on a 2,500 residue protein but we requested four GPUs to have sufficient memory."
122	122
	123	+The following environment variable settings may help with larger polypeptide calculations (> 1,200 aa).
	124	+
	125	+```
	126	+TF_FORCE_UNIFIED_MEMORY=1
	127	+XLA_PYTHON_CLIENT_MEM_FRACTION=0.5
	128	+XLA_PYTHON_CLIENT_ALLOCATOR=platform
	129	+```
	130	+Thanks Ci Ji Lim at Wisconsin for suggesting and testing these.
123	131	### pTM scores
124	132	The pTM scores are not calculated using the default model. To get pTM scored models you need to change the model names in the input. We have provided a template wrapper script (https://sbgrid.org//wiki/examples/alphafold2) which you can change to your requirements. To get pTM scores you will need to change the model_name line to "model_1_ptm,model_2_ptm" etc.
125	133