fix whitespace

Author: swhite2

source/manual/dhcp.rst

@@ -28,7 +28,7 @@ Reservations
 Both ISC DHCP and KEA DHCP offer the possibility to reserve an IP address for a specific client. This is useful when a client
 needs to have the same IP address every time it connects to the network. Both services also offer the ability to define reservations
 inside and outside of the assigned pool of dynamic IP addresses. However, you should only define reservations outside of the pool.
-Unless you can guarantee that this client is online at all times when the reservation is in the dynamic range, the DHCP server is 
+Unless you can guarantee that this client is online at all times when the reservation is in the dynamic range, the DHCP server is
 free to offer this IP address to a different client when the first client goes offline.
 
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