Update bb instructions

Summary: The kubectl was missing a apply.

Test Plan: N/A

Reviewers: michelle, zasgar

Reviewed By: michelle
Signed-off-by: Vihang Mehta <vihang@pixielabs.ai>

Differential Revision: https://phab.corp.pixielabs.ai/D10597

GitOrigin-RevId: 7ca771487b7eee6d1997d0f055a7a0b9e78eb461

k8s/devinfra/buildbuddy/README.md

-# Managed by Helm.
-## Install instructions:
+# Managed by Helm
+
+## Install instructions
 
 ```
 helm repo add buildbuddy https://helm.buildbuddy.io
@@ -7,7 +8,7 @@ helm repo update
 
 # Install secrets.
 kubectl create namespace buildbuddy
-sops -d $(bazel info workspace)/credentials/dev_infra/buildbuddy/sa_secret.yaml | kubectl -n buildbuddy -f -
+sops -d $(bazel info workspace)/credentials/dev_infra/buildbuddy/sa_secret.yaml | kubectl apply -n buildbuddy -f -
 
 # Get the config.
 sops -d $(bazel info workspace)/credentials/dev_infra/buildbuddy/config.yaml > config.yaml