Add a few Russian pedagogical publications

[kcrisman]

See https://groups.google.com/forum/#!topic/sage-edu/WUeR22LkWgs for these:

1. Alexander Kuvaev. The Sage computer algebra system: installation and programming elements. Ivanovo: Ivanovo State University, 2013. 35 p. (In Russian)
2. Nickolai Yatskin. Algebraic computations in the Sage system. Ivanovo: Ivanovo State University, 2014. 47 p. (In Russian) {Linear algebra, polynomial rings, finite fields, groups.}
3. Nickolai Yatskin. Z[i] and other rings (computations using Sage). Ivanovo: Ivanovo State University, 2015. 88 p. (In Russian) [electronic resource] {Algorithms in algebraic number fields and rings.}
4. Nickolai Yatskin. Computer algebra. Laboratory practicum using Sage. Moscow: "Vuzovskaya kniga", 2016. 94 p. (In Russian) {Laboratory works: the Euclid algorithm in polynomial and Gaussian integer rings; the factorization algorithms for Gaussian integers and polynomials over integers; finite fields and the Berlekamp algorithm.}