docs: Update add customer agent command
Update the developer guide to correct the
command that adds a customer kata-agent to the rootfs image
putting it in /usr/bin/kata-agent rather than /bin/kata-agent
Fixes
@@ -304,7 +304,7 @@ You MUST choose one of `alpine`, `centos`, `clearlinux`, `debian`, `euleros`, `f
> - You should only do this step if you are testing with the latest version of the agent.
```
-$ sudo install -o root -g root -m 0550 -t ${ROOTFS_DIR}/bin ../../../src/agent/target/x86_64-unknown-linux-musl/release/kata-agent
+$ sudo install -o root -g root -m 0550 -t ${ROOTFS_DIR}/usr/bin ../../../src/agent/target/x86_64-unknown-linux-musl/release/kata-agent
$ sudo install -o root -g root -m 0440 ../../../src/agent/kata-agent.service ${ROOTFS_DIR}/usr/lib/systemd/system/
$ sudo install -o root -g root -m 0440 ../../../src/agent/kata-containers.target ${ROOTFS_DIR}/usr/lib/systemd/system/
```
