Update merge.rst

Typo in first line:
The merge filter merges an array with [removed: the] another array
merged branch carlwitt/patch-1 (PR #1022)

This PR was merged into the master branch.

Commits
-------

59d0eed Update merge.rst

Discussion
----------

Update merge.rst

Typo in first line:
The merge filter merges an array with [removed: the] another array