Correct memory size docs

docs/Training-PPO.md

 
 `memory_size` corresponds to the size of the array of floating point numbers
 used to store the hidden state of the recurrent neural network of the policy. This value must
-be a multiple of 4, and should scale with the amount of information you expect
+be a multiple of 2, and should scale with the amount of information you expect
 the agent will need to remember in order to successfully complete the task.
 
 Typical Range: `32` - `256`

docs/Training-SAC.md

 
 `memory_size` corresponds to the size of the array of floating point numbers
 used to store the hidden state of the recurrent neural network in the policy.
-This value should scale with the amount of information you expect
+This value must be divisible by 2, and should scale with the amount of information you expect
 the agent will need to remember in order to successfully complete the task.
 
 Typical Range: `32` - `256`