Increase details in docs

doc/zmq_ctx_set.txt

@@ -64,9 +64,11 @@ ZMQ_THREAD_PRIORITY: Set scheduling priority for I/O threads
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The 'ZMQ_THREAD_PRIORITY' argument sets scheduling priority for
 internal context's thread pool. This option is not available on windows.
-When the scheduler policy is SCHED_OTHER on Linux, the system call "nice"
-will be used to set a priority of -20 (max priority).
 Supported values for this option depend on chosen scheduling policy.
+On Linux, when the scheduler policy is SCHED_OTHER, SCHED_IDLE or SCHED_BATCH, the OS scheduler
+will not use the thread priority but rather the thread "nice value"; in such cases
+the system call "nice" will be used to set the nice value to -20 (max priority) instead of
+adjusting the thread priority (which must be zero for those scheduling policies).
 Details can be found in sched.h file, or at http://man7.org/linux/man-pages/man2/sched_setscheduler.2.html.
 This option only applies before creating any sockets on the context.
 
@@ -78,6 +80,10 @@ ZMQ_THREAD_AFFINITY: Set CPU affinity for I/O threads
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The 'ZMQ_THREAD_AFFINITY' argument sets CPU affinity for the internal
 context's thread pool. This option is only supported on Linux.
+On Linux, each bit of the 'option_value' argument will represent an enabled
+CPU in the corresponding cpu_set_t; for example the value 0x1 will set affinity
+of all context's thread pool to CPU 0; the value 0x110 will set affinity
+of all context's thread pool to CPU 1 and 2.
 This option only applies before creating any sockets on the context.
 
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