Add info on Brian's Brain

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+Brian's Brain
+=============
+
+https://en.wikipedia.org/wiki/Brian%27s_Brain
+https://en.wikipedia.org/wiki/Brian_Silverman
+
+> Brian's Brain is a cellular automaton devised by Brian Silverman, which is
+> very similar to his Seeds rule.
+>
+> Rules
+> -----
+> Brian's Brain consists of an infinite two-dimensional grid of cells, but
+> unlike Seeds, each cell may be in one of three states: on, dying, or off.
+> Each cell is considered to have eight neighbors (the Moore neighborhood), as
+> in Seeds and Conway's Game of Life.
+>
+> In each time step, a cell turns on if it was off but had exactly two
+> neighbors that were on, just like the birth rule for Seeds. All cells that
+> were "on" go into the "dying" state, which is not counted as an "on" cell in
+> the neighbor count, and prevents any cell from being born there. Cells that
+> were in the dying state go into the off state.