fix(DOC-1681): sentence-case headings in broker properties reference (#1609)

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: mfernest

modules/reference/pages/properties/broker-properties.adoc

@@ -47,7 +47,7 @@ redpanda:
 include::reference:partial$properties/broker-properties.adoc[tags=category-redpanda;!deprecated;!exclude-from-docs]
 
 [[http_based_auth_method]]
-== HTTP-Based Authentication
+== HTTP-based authentication
 
 The `authentication_method` property configures authentication for HTTP-based API listeners (Schema Registry and HTTP Proxy).
 
@@ -97,7 +97,7 @@ schema_registry:
 include::reference:partial$properties/broker-properties.adoc[tags=category-schema-registry;!deprecated;!exclude-from-docs]
 
 
-== HTTP Proxy Client
+== HTTP Proxy client
 
 Configuration options for how the HTTP Proxy **connects to Kafka brokers**. 
 
@@ -130,9 +130,9 @@ Replace the following placeholders with your values:
 
 include::reference:partial$properties/broker-properties.adoc[tags=category-pandaproxy-client;!deprecated;!exclude-from-docs]
 
-== Schema Registry Client
+== Schema Registry client
 
-Configuration options for Schema Registry Client connections to Kafka brokers.
+Configuration options for Schema Registry client connections to Kafka brokers.
 
 .Example
 [,yaml]
@@ -159,13 +159,13 @@ Replace the following placeholders with your values:
 * `<username>`: SCRAM username for authentication
 * `<password>`: SCRAM password for authentication
 
-NOTE: Schema Registry Client uses the same configuration properties as HTTP Proxy Client but with different defaults optimized for Schema Registry operations. The client uses immediate batching (0ms delay, 0 record count) for low-latency schema operations.
+NOTE: Schema Registry client uses the same configuration properties as HTTP Proxy client but with different defaults optimized for Schema Registry operations. The client uses immediate batching (0 ms delay, 0 record count) for low-latency schema operations.
 
 ---
 
-== Audit Log Client
+== Audit log client
 
-Configuration options for Audit Log Client connections to Kafka brokers.
+Configuration options for Audit log client connections to Kafka brokers.
 
 .Example
 [,yaml]