tools lib traceevent: Man page for tep_read_number()

Create man page for tep_read_number() libtraceevent API.
Signed-off-by: Tzvetomir Stoyanov <tstoyanov@vmware.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: linux-trace-devel@vger.kernel.org
Link: http://lore.kernel.org/linux-trace-devel/20190503091119.23399-14-tstoyanov@vmware.com
Link: http://lkml.kernel.org/r/20190510200108.042164597@goodmis.orgSigned-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/lib/traceevent/Documentation/libtraceevent-endian_read.txt

+libtraceevent(3)
+================
+
+NAME
+----
+tep_read_number - Reads a number from raw data.
+
+SYNOPSIS
+--------
+[verse]
+--
+*#include <event-parse.h>*
+
+unsigned long long *tep_read_number*(struct tep_handle pass:[*]_tep_, const void pass:[*]_ptr_, int _size_);
+--
+
+DESCRIPTION
+-----------
+The _tep_read_number()_ function reads an integer from raw data, taking into
+account the endianness of the raw data and the current host. The _tep_ argument
+is the trace event parser context. The _ptr_ is a pointer to the raw data, where
+the integer is, and the _size_ is the size of the integer.
+
+RETURN VALUE
+------------
+The _tep_read_number()_ function returns the integer in the byte order of
+the current host. In case of an error, 0 is returned.
+
+EXAMPLE
+-------
+[source,c]
+--
+#include <event-parse.h>
+...
+struct tep_handle *tep = tep_alloc();
+...
+void process_record(struct tep_record *record)
+{
+	int offset = 24;
+	int data = tep_read_number(tep, record->data + offset, 4);
+
+	/* Read the 4 bytes at the offset 24 of data as an integer */
+}
+...
+--
+
+FILES
+-----
+[verse]
+--
+*event-parse.h*
+	Header file to include in order to have access to the library APIs.
+*-ltraceevent*
+	Linker switch to add when building a program that uses the library.
+--
+
+SEE ALSO
+--------
+_libtraceevent(3)_, _trace-cmd(1)_
+
+AUTHOR
+------
+[verse]
+--
+*Steven Rostedt* <rostedt@goodmis.org>, author of *libtraceevent*.
+*Tzvetomir Stoyanov* <tz.stoyanov@gmail.com>, author of this man page.
+--
+REPORTING BUGS
+--------------
+Report bugs to  <linux-trace-devel@vger.kernel.org>
+
+LICENSE
+-------
+libtraceevent is Free Software licensed under the GNU LGPL 2.1
+
+RESOURCES
+---------
+https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git