add ready examples to docstring for rselect, rtransform (JuliaData#321)

src/macros.jl

@@ -1403,8 +1403,33 @@ end
 """
     @rtransform(x, args...)
 
-Row-wise version of `@transform`, i.e. all operations use `@byrow` by
-default. See [`@transform`](@ref) for details.
+Row-wise version of `@transform`, i.e. all operations use `@byrow` by default.
+See [`@transform`](@ref) for details.
+
+### Examples
+```jldoctest
+julia> df = DataFrame(x = 1:5, y = 11:15)
+5×2 DataFrame
+ Row │ x      y
+     │ Int64  Int64
+─────┼──────────────
+   1 │     1     11
+   2 │     2     12
+   3 │     3     13
+   4 │     4     14
+   5 │     5     15
+
+julia> @rtransform(df, :a = :x + :y ^ 2, :c = :y == 13 ? 999 : 1 - :y)
+5×4 DataFrame
+ Row │ x      y      a      c
+     │ Int64  Int64  Int64  Int64
+─────┼────────────────────────────
+   1 │     1     11    122    -10
+   2 │     2     12    146    -11
+   3 │     3     13    172    999
+   4 │     4     14    200    -13
+   5 │     5     15    230    -14
+```
 """
 macro rtransform(x, args...)
     esc(rtransform_helper(x, args...))
@@ -1659,6 +1684,31 @@ end
 
 Row-wise version of `@select`, i.e. all operations use `@byrow` by
 default. See [`@select`](@ref) for details.
+
+### Examples
+```jldoctest
+julia> df = DataFrame(x = 1:5, y = 10:14)
+5×2 DataFrame
+ Row │ x      y
+     │ Int64  Int64
+─────┼──────────────
+   1 │     1     10
+   2 │     2     11
+   3 │     3     12
+   4 │     4     13
+   5 │     5     14
+
+julia> @rselect(df, :x, :A = mod(:y, :x) == 0 ? 99 : :x)
+5×2 DataFrame
+ Row │ x      A
+     │ Int64  Int64
+─────┼──────────────
+   1 │     1     99
+   2 │     2      2
+   3 │     3     99
+   4 │     4      4
+   5 │     5      5
+```
 """
 macro rselect(x, args...)
     esc(rselect_helper(x, args...))