Fix typo: multiple tuple => tuples

[houzj.f...@fujitsu.com]

Hi,

I found a possible typo in the code comments of heap_multi_insert.

- *     heap_multi_insert       - insert multiple tuple into a heap
+ *     heap_multi_insert       - insert multiple tuples into a heap

Attaching a patch to fix it.

Best regards,
houzj

0001-fix-typo.patch
Description: 0001-fix-typo.patch