Apply suggestions from code review

Co-authored-by: Leonard Ehrenfried <[email protected]>

docs/sandbox/VehicleRentalServiceDirectory.md

@@ -63,9 +63,9 @@ HTTP headers to add to the request. Any header key, value can be inserted.
 
 List all networks to include. Use "network": "default-network" to set defaults.
 
-If no default network exist only the listed networks are used. Configure the a network with
+If no default network exists only the listed networks are used. Configure a network with
 name "default-network" to include all unlisted networks. If not present, all unlisted
-networks is dropped. Note! The values in the "default-network" are not used to set
+networks are dropped. Note! The values in the "default-network" are not used to set
 missing field values in networks listed.
 
 

src/main/java/org/opentripplanner/standalone/config/sandbox/VehicleRentalServiceDirectoryFetcherConfig.java

@@ -63,9 +63,9 @@ private static List<NetworkParameters> mapNetworkParameters(
       )
       .description(
         """
-        If no default network exist only the listed networks are used. Configure the a network with
+        If no default network exists only the listed networks are used. Configure a network with
         name "{{default-network}}" to include all unlisted networks. If not present, all unlisted
-        networks is dropped. Note! The values in the "{{default-network}}" are not used to set
+        networks are dropped. Note! The values in the "{{default-network}}" are not used to set
         missing field values in networks listed.
         """.replace(
             "{{default-network}}",