Fix minor text issues on mapping page

[tobiasgf]

"Unmapped fields
Here is a list of the fields in your data that has not yet been mapped to a standard field name.

Not all fields does neccessarily map to standard fields in a logical sense.

Unmapped fields will stil be available in the BIOM files created in the next step, but they will not be in the Darwin Core achive unless you include them as a measurement."

change to:

"Unmapped fields

Fields in your data that have not been mapped to a standard field name (DwC term).

Not all fields may necessarily be possible to map to standard fields (DwC terms).

Unmapped fields will still be available in the BIOM files created in the next step, but they will not be included in the Darwin Core achive unless they are included as a measurement."

AND

"No unmapped fields
Click a field to include as a measurement. Fields selected as measurements will be included in the Extended Measurement Or Facts extension for Darwin core"

change to

"No unmapped fields
Click a field to include it as a measurement. Fields selected as measurements will be included in the Extended Measurement Or Facts extension for Darwin Core."

AND

remove final ":" from
Fields for inclusion in the Extended Measurement Or Facts extension: