Update README.md

Author: markisus

README.md

@@ -1,8 +1,9 @@
 # vapid soa
 A simple header only library that implements structure of arrays data structure backed by std::vector.  
 These are the most useful operations.  
+- `.insert(field1, field2, ...)` field_n inserts into the nth array
 - `.sort_by_field<col_idx>()` sort all columns in tandem based on particular column 
-- `operator[row_idx]` read data out as tuple of references
+- `.operator()[row_idx]` read data out as tuple of references
 - `.get_column<col_idx>()` direct access to underlying std::vector column
 - `.view<col_idx1, col_idx2, ...>()` read subset of the columns out as a tuple of references