Update install.rst so joke is more scientifically accurate (#384)

Replaced the word venomous with vicious, since anacondas are not venomous :)

doc/src/install.rst

@@ -32,7 +32,7 @@ beartype will be there.
 
  pip3 install beartype
 
-Install beartype with Anaconda_, because package managers named after venomous
+Install beartype with Anaconda_, because package managers named after vicious 
 South American murder reptiles have finally inspired your team to embrace more
 mammal-friendly packages. Your horoscope also reads: "Avoid reckless ecotourism
 in places that rain alot."