init commit of examples

Examples/SPISLAVEDMA/SPISLAVEDMA(3)/documentation/stdio.rst

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+STDIO redirection
+=================
+
+The STDIO redirection provides means to redirect standard input/output to HAL
+IO.
+
+On initialization, the HAL IO descriptor is assigned so that all input and
+output is redirected to access it. The IO descriptor can also be changed
+through stdio_io_set_io(). All stdin or stdout access is redirected to the
+IO descriptor. When the IO descriptor is set to NULL, all input and output 
+are discarded.
+
+For GCC redirection, the stdout and stdin buffer are turned off, the
+standard _read() and _write() are overridden.
+
+For IAR redirection, the __read() and __write() are overridden.
+
+For Keil redirection, the Retarget.c are modified to override fputc(), fgetc(),
+etc.
+
+Features
+--------
+
+* Standard input/output redirection (e.g., printf to EDBG COM port)
+
+Dependencies
+------------
+
+* HAL IO driver
+
+Limitations
+-----------
+
+* IO read/write operation should be synchronous