Add a "known issues & limitations" page

[leofang]

• cuda.core does not allow any side calls to cudaDeviceReset or alike that tear down the primary contexts
• avoid multiple frees of the same buffer in the child process (IPC tests do not exit cleanly #1074 (comment), [BUG]: Errors occurring in Buffer.close are not raised #1118)
• when going out of scope without an explicit .close() call, a buffer is deallocated on the allocation stream (Ensure allocation stream is used for buffer deallocation if no explicit stream is provided #1032)
• compute-sanitizer needs a flag to work with cuda.core ([BUG]: compute-sanitzer finds CUDA_ERROR_INVALID_CONTEXT with default Device constructor #562 (comment))
• ...