pgsql: Fix description of I/O timing info for shared buffers in EXPLAIN

Fix description of I/O timing info for shared buffers in EXPLAIN (BUFFERS) This fixes an error introduced by efb0ef909f60, that changed the description of this field to "shared/local" while these I/O timings relate to shared buffers. This information is available when track_io_timing is enabled.

pgsql: Fix description of I/O timing info for shared buffers in EXPLAIN

Fix description of I/O timing info for shared buffers in EXPLAIN (BUFFERS) This fixes an error introduced by efb0ef909f60, that changed the description of this field to "shared/local" while these I/O timings relate to shared buffers. This information is available when track_io_timing is enabled.