rangeproof: typo fix y^-n -> y^-nm (#237)

Author: kevaundray

docs/range-proof-protocol.md

@@ -189,7 +189,7 @@ The goal of the verifier is to check two equations:
   Rewriting as a comparison with the identity point and expanding \\(Q = wB\\) and \\(P' = P + t(x) wB\\) as [needed for transition to the inner-product protocol](../notes/index.html#inner-product-proof):
 
   \\[
-  0 \overset ? = P + t(x) wB - {\langle a \cdot {\mathbf{s}}, {\mathbf{G}} \rangle} - {\langle {\mathbf{y}^{-n}} \circ (b /{\mathbf{s}}), {\mathbf{H}} \rangle} - abwB + \sum\_{j=1}^{k} \left( L\_{j} u\_{j}^{2} + u\_{j}^{-2} R\_{j} \right),
+  0 \overset ? = P + t(x) wB - {\langle a \cdot {\mathbf{s}}, {\mathbf{G}} \rangle} - {\langle {\mathbf{y}^{-n \cdot m}} \circ (b /{\mathbf{s}}), {\mathbf{H}} \rangle} - abwB + \sum\_{j=1}^{k} \left( L\_{j} u\_{j}^{2} + u\_{j}^{-2} R\_{j} \right),
   \\]
   where the [definition](../notes/index.html#proving-that-mathbflx-mathbfrx-are-correct-1) of \\(P\\) is: