Typos in algebra.tex and topology.tex

Thanks to Wei Xu
http://stacks.math.columbia.edu/tag/0581#comment-624
http://stacks.math.columbia.edu/tag/00CX#comment-625
http://stacks.math.columbia.edu/tag/00E5#comment-626
http://stacks.math.columbia.edu/tag/00CZ#comment-627
http://stacks.math.columbia.edu/tag/0406#comment-628
http://stacks.math.columbia.edu/tag/0377#comment-629
http://stacks.math.columbia.edu/tag/07VB#comment-630
http://stacks.math.columbia.edu/tag/004Z#comment-631
http://stacks.math.columbia.edu/tag/037A#comment-632