Update non-function use of "thru" to "through"

[mjoyce91]

It's possible that someone at some point did a find-and-replace for the word "through" and changed it to "thru", since that is a lodash function. However, this spelling is not appropriate in all cases, such as when it is the use of the non-function word "through". This seems to be the case as the older versions of the docs used the correct spelling of "through".

This resolves https://github.com/lodash/lodash/issues/4861