Add missing function alias to documentation

[matildasmeds]

contains has two aliases include and includes
This patch adds include to documentation

[coveralls]

Coverage remained the same at 96.763% when pulling 255acbf on matildasmeds:add_missing_alias_to_doc into 67e43b6 on jashkenas:master.

[captbaritone]

Thanks for this! Could you also update the data-aliases attribute in the table of contents so that search works properly for this alias?

[matildasmeds]

Updated.

[coveralls]

Coverage remained the same at 96.763% when pulling 25fce7d on matildasmeds:add_missing_alias_to_doc into 67e43b6 on jashkenas:master.

[captbaritone]

Thanks! Might as well be explicit.

[captbaritone]

I'll cherry pick this onto fh-pages later today.