Update _index.adoc

Only one of the fields participates in the Tab focus cycle so Tab doesn't switch between fields.

documentation/content/en/books/handbook/bsdinstall/_index.adoc

@@ -581,7 +581,7 @@ The other partition schemes are generally used for uncommon or older computers.
 |===
 
 After the partitioning scheme has been selected and created, select btn:[Create] again to create the partitions.
-The kbd:[Tab] key is used to move the cursor between fields.
+The kbd:[Tab] key is used to give focus to the fields (after cycling through btn:[<OK>], btn:[<Options>], and btn:[<Cancel>]). 
 
 [[bsdinstall-part-manual-addpart]]
 .Manually Create Partitions