I#56 - README: Correct typo
I#56 - README: Correct typo

Assuming it was 'pipe-lining' and not 'piping', here's a correction to 'pipe-ling', which may not be English.

Closes https://gitlab.gnome.org/GNOME/evolution-ews/issues/56

GNOME/evolution-ews,GNOME/evolution-ews