HDDS-14465. Update 'Bucket Level Default Replication Type' documentation

docs/03-core-concepts/03-namespace/02-buckets/05-default-replication.mdx

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+---
+title: Default Bucket Replication
+sidebar_label: Default Replication
+---
+
+# Default Bucket Replication
+
+The data redundancy for keys within an Apache Ozone bucket is determined by a replication configuration (type and value). This configuration can be set as an explicit default on the bucket itself, or it can be inherited from cluster-wide defaults if not set on the bucket. This document explains this process.
+
+## Setting a Default Replication on a Bucket
+
+When a bucket is created, a default replication configuration can be explicitly stored on the bucket. This bucket-level default will apply to all keys created within it, unless a key is written with its own specific replication override.
+
+Ozone uses the following order of precedence to set a default replication property **on a bucket** during creation:
+
+1.  **Explicit Flags:** Using both the `--type` and `--replication` flags in the `ozone sh bucket create` command. This is the most direct way to set a bucket's default replication.
+2.  **Client-Side Value with Type Flag:** Using the `--type` flag during bucket creation in combination with the `ozone.replication` property set in the client's `ozone-site.xml`.
+
+**Example:**
+If `ozone.replication=1` is set on the client, the following command sets the default replication for `bucket2` to `RATIS-1`:
+```bash
+ozone sh bucket create vol1/bucket2 -t RATIS
+```
+
+## Fallback to Cluster-Wide Defaults
+
+If no default replication is set on the bucket during creation (i.e., neither of the methods above is used), the bucket is created **without** an explicit default replication property.
+
+In this scenario, any key created within that bucket will fall back to using the cluster-wide default replication settings defined in the Ozone Manager's `ozone-site.xml`.
+
+```xml
+  <property>
+    <name>ozone.server.default.replication.type</name>
+    <value>RATIS</value>
+    <tag>OZONE</tag>
+    <description>
+      The cluster-wide default replication type (e.g., RATIS, EC) used for keys
+      when their bucket has no default replication set.
+    </description>
+  </property>
+  <property>
+    <name>ozone.server.default.replication</name>
+    <value>3</value>
+    <tag>OZONE</tag>
+    <description>
+      The cluster-wide default replication value used for keys when their
+      bucket has no default replication set.
+      <ul>
+        <li><b>For RATIS:</b> 1, 3</li>
+        <li><b>For EC (Erasure Coding):</b> Formatted as {Codec}-{Data}-{Parity}-{ChunkSize}.
+          <ul>
+            <li><b>Codec:</b> XOR, RS</li>
+            <li><b>Data-Parity Blocks:</b> 3-2, 6-3, 10-4</li>
+            <li><b>ChunkSize:</b> e.g., 1024k, 2048k</li>
+          </ul>
+        </li>
+      </ul>
+    </description>
+  </property>
+```
+
+**Example:**
+If you run `ozone sh bucket create vol1/bucket1` (with no flags or client properties), the bucket `bucket1` is created with no default replication. When a key is later written to `bucket1` without a specific replication override, it will use the cluster-wide server defaults (e.g., `RATIS-3`).