TLS configuration: Add Content-Type

Redfish and HTTP rule. Better if correct everywhere.

bmcweb is attempting to validate content-type header,
https://gerrit.openbmc.org/c/openbmc/bmcweb/+/59941.

Change-Id: Ic51d9308e11c34771d1e2298cebc488951bc6dc3
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
diff --git a/security/TLS-configuration.md b/security/TLS-configuration.md
index 1ad819c..fddb1b8 100644
--- a/security/TLS-configuration.md
+++ b/security/TLS-configuration.md
@@ -354,7 +354,7 @@
 environment variable.
 
 ```
-curl --user root:0penBmc -d @install_ca.json -k -X POST https://${bmc}/redfish/v1/Managers/bmc/Truststore/Certificates
+curl --user root:0penBmc -d @install_ca.json -k -H "Content-Type: application/json" -X POST https://${bmc}/redfish/v1/Managers/bmc/Truststore/Certificates
 
 ```
 
@@ -391,7 +391,7 @@
 `replace_cert.json` with this command:
 
 ```
-curl --user root:0penBmc -d @replace_cert.json -k -X POST https://${bmc}/redfish/v1/CertificateService/Actions/CertificateService.ReplaceCertificate/
+curl --user root:0penBmc -d @replace_cert.json -k -H "Content-Type: application/json" -X POST https://${bmc}/redfish/v1/CertificateService/Actions/CertificateService.ReplaceCertificate/
 
 ```