Add documentation for how buffers are managed in runtime.

Author: sherry-yuan

docs/buffers.md

@@ -0,0 +1,15 @@
+# Buffers
+
+## Summary
+
+1. Buffers are not actually allocated on device until the kernel execute, unless clEnqueueWriteBuffer are called
+2. 
+
+
+
+## How are buffers allocated on device
+
+## When are buffers allocated on device
+
+## The flow
+clCreateBufferWithPropertiesINTEL https://github.com/intel/fpga-runtime-for-opencl/blob/b08e0af97351718ce0368a9ee507242b35f4929e/src/acl_mem.cpp#L408-L953