[docs] Add missing slash to avoid empty cell
[docs] Add missing slash to avoid empty cell

A missing slash in the end `</td>` tag of field cell for Delphi and
.NET Standard was generating an additional empty cell, breaking the
table (and generating misleading info).

[skip ci]

apache/thrift,apache/thrift,Jens-G/thrift,Jens-G/thrift,apache/thrift,Jens-G/thrift,Jens-G/thrift,Jens-G/thrift,apache/thrift,Jens-G/thrift,Jens-G/thrift,apache/thrift,apache/thrift,apache/thrift,Jens-G/thrift,Jens-G/thrift,Jens-G/thrift,apache/thrift,apache/thrift,Jens-G/thrift,Jens-G/thrift,apache/thrift,apache/thrift,Jens-G/thrift,apache/thrift,apache/thrift,Jens-G/thrift,Jens-G/thrift,apache/thrift,Jens-G/thrift,Jens-G/thrift,Jens-G/thrift,apache/thrift,apache/thrift,apache/thrift,apache/thrift