Add basement-swim page linked from  eating-chocolate page

I modified 'english/light-fire/sprinkler/eating-chocolate.md'. Now the basement is flooded with chocolate and there is one more choice (swim in the chocolate pool), which means there is another subdirectory and page added (basement-swim/basement-swim.md).
Again, thanks for breaking up this sentence into multiple lines, but please delete the blank line (line 6).