Update source/retryable-reads/retryable-reads.rst

Co-authored-by: Alex Bevilacqua <alex@alexbevi.com>

source/retryable-reads/retryable-reads.rst

@@ -268,7 +268,7 @@ selecting a server for a retry attempt.
 3a. Selecting the server for retry
 ''''''''''''''''''''''''''''''''''
 
-Server on wich the operation failed MUST be provided to the server selection
+Server on which the operation failed MUST be provided to the server selection
 mechanism as a de-prioritized server. If the driver cannot select a server for
 a retry attempt or the newly selected server does not support retryable reads,
 retrying is not possible and drivers MUST raise the previous retryable error.