Fix reference to Unicorn in Puma section

doc/install/requirements.md

@@ -189,7 +189,7 @@ To change the Unicorn workers when you have the Omnibus package (which defaults
 ## Puma Workers
 
 For most instances we recommend using: max(CPU cores * 0.9, 2) = Puma workers.
-For example a node with 4 cores would have 3 Unicorn workers.
+For example a node with 4 cores would have 3 Puma workers.
 
 For all machines that have 4GB and up we recommend a minimum of three Puma workers.
 If you have a 2GB machine we recommend to configure only one Puma worker to prevent excessive swapping.