Fix grammar in description of SetColumns method

grid.go

@@ -77,8 +77,8 @@ func NewGrid() *Grid {
 
 // SetColumns defines how the columns of the grid are distributed. Each value
 // defines the size of one column, starting with the leftmost column. Values
-// greater 0 represent absolute column widths (gaps not included). Values less
-// or equal 0 represent proportional column widths or fractions of the remaining
+// greater than 0 represent absolute column widths (gaps not included). Values less
+// than or equal to 0 represent proportional column widths or fractions of the remaining
 // free space, where 0 is treated the same as -1. That is, a column with a value
 // of -3 will have three times the width of a column with a value of -1 (or 0).
 // The minimum width set with SetMinSize() is always observed.