Set the column title.
The titles of columns are typically read directly from the DOM (from the cells in the
THEAD element), but it can often be useful to either override existing values, or have DataTables actually construct a header with column titles for you (for example if there is not
THEAD element in the table before DataTables is constructed). This option is available to provide that ability.
Please note that when constructing a header, DataTables can only construct a simple header with a single cell for each column. Complex headers with
rowspan attributes must either already be defined in the document, or be constructed using standard DOM / jQuery methods.
This option can be given in the following type(s):
Value read from the column's header cell.