Use consistent config file name

Author: willshen

docs/installation.md

@@ -198,7 +198,7 @@ JAR and YAML files:
 
 ```shell
 java -XX:MinRAMPercentage=50 -XX:MaxRAMPercentage=80 \
-    -jar gateway-ha.jar gateway-config.yml
+    -jar gateway-ha.jar gateway-ha-config.yml
 ```
 
 ### Helm <a name="helm"></a>

docs/migration-to-airlift.md

@@ -139,12 +139,12 @@ The first arg `server` has been removed.
 
 Old config:
 ```bash
-java -jar gateway-ha.jar server gateway-config.yml
+java -jar gateway-ha.jar server gateway-ha-config.yml
 ```
 
 New config:
 ```bash
-java -jar gateway-ha.jar gateway-config.yml
+java -jar gateway-ha.jar gateway-ha-config.yml
 ```
 
 ### Format of `extraWhitelistPaths`