fix typo in description of watts_strogatz(n, k, β) (#169)

effect of β is the other way round

Author: ChristianStehr

src/SimpleGraphs/generators/randgraphs.jl

@@ -262,7 +262,7 @@ where each vertex has exacly `div(k, 2)` neighbors on each side (i.e., `k` or
    connected to some vertex `d`, chosen uniformly at random from the entire
    graph, excluding `s` and its neighbors. (Note that `t` is a valid candidate.)
 
-For `β = 1`, the graph will remain a 1-lattice, and for `β = 0`, all edges will
+For `β = 0`, the graph will remain a 1-lattice, and for `β = 1`, all edges will
 be rewired randomly.
 
 ### Optional Arguments