added note to replace ECC diagrams with ones showing correct points

ch04.asciidoc

@@ -29,7 +29,7 @@ In most implementations, the private and public keys are stored together as a _k
 ((("elliptic curve cryptography", "ECC")))
 Elliptic Curve Cryptography is a type of asymmetric or public-key cryptography based on the discrete logarithm problem as expressed by addition and multiplication on the points of an elliptic curve. 
 
-
+<< Replace chart below with one showing the K = k * G key generation as a line on the curve >>
 
 [[ecc_addition]]
 .Elliptic Curve Cryptography: Visualizing the addition operator on the points of an elliptic curve
@@ -56,6 +56,8 @@ where +latexmath:[\(p = 2^256 - 2^32 - 2^9 - 2^8 - 2^7 - 2^6 - 2^4 - 1\)]+, a ve
 
 The +mod p+ indicates that this curve is over a finite field of prime order +p+, also written as latexmath:[\(\mathbb{F}_p\)]. The curve looks like a pattern of dots scattered in two dimensions, which makes it difficult to visualize. However, the math is identical as that of an elliptic curve over the real numbers shown above.
 
+<< Replace chart below with one showing the K = k * G key generation as a line on the curve >>
+
 [[ecc-over-F37-math]]
 .Elliptic Curve Cryptography: Visualizing the addition operator on the points of an elliptic curve over F(p)
 image::images/ecc-over-F37-math.png["Addition operator on points of an elliptic curve over F(p)"]