small typo correction (#1438)
small typo correction (#1438)

Co-authored-by: nchampollion <4c236522e7e5e2e5a027c4df8b279d2115ed17cc@gmail.com>
OGGM/oggm,bearecinos/oggm,TimoRoth/oggm,anoukvlug/oggm,anoukvlug/oggm,TimoRoth/oggm,OGGM/oggm,bearecinos/oggm