Fix small typo in DEVELOPER_GUIDE.md (#17512)

Signed-off-by: Eric Pugh <epugh@opensourceconnections.com>

Author: epugh

DEVELOPER_GUIDE.md

@@ -127,7 +127,7 @@ All distributions built will be under `distributions/archives`.
 #### Generated Code
 
 OpenSearch uses code generators like [Protobuf](https://protobuf.dev/).
-OpenSearch build system already takes a dependency of generating code from protobuf, incase you run into compilation errors, run:
+OpenSearch build system already takes a dependency of generating code from protobuf, if you run into compilation errors, run:
 
 ```
 ./gradlew generateProto