add man pages for buffer_from*

buffer/buffer_fromarray.3

@@ -0,0 +1,19 @@
+.TH buffer_fromarray 3
+.SH NAME
+buffer_fromarray \- initialize buffer structure from array
+.SH SYNTAX
+.B #include <array.h>
+.B #include <buffer.h>
+
+void \fBbuffer_fromarray\fR(buffer* \fIb\fR,array* \fIa\fR);
+.SH DESCRIPTION
+buffer_fromarray makes a virtual read buffer from an array.  The buffer
+reading functions will be able to read until the end of the data in the
+array, then signal EOF.  The buffer does not have its own buffer
+space, it reuses the one in the array.
+
+Do not touch the array until you are done with the buffer!
+
+Reading data from the buffer will not change the stralloc.
+.SH "SEE ALSO"
+buffer_fromsa(3), buffer_init(3), buffer(3), buffer_frombuf(3)