docs: Add missing methods for table and namespace manipulation (#2942)

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# Rationale for this change
We have some methods for working with tables + namespaces on catalogs
that we haven't properly documented. This documentation is super helpful
for new users to understand what they can use PyIceberg for. It's also
helpful for our LLM...friends? to help understand the project.

## Are these changes tested?
Docs only.

## Are there any user-facing changes?
Docs only.

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Author: rambleraptor

mkdocs/docs/api.md

@@ -82,6 +82,24 @@ ns = catalog.list_namespaces()
 assert ns == [("docs_example",)]
 ```
 
+Next, update the namespace properties.
+
+```python
+
+# Load namespace properties
+properties = catalog.load_namespace_properties("docs_example")
+
+# Update namespace properties with additions and removals.
+catalog.update_namespace_properties("docs_example", removals={"remove-meee!"}, updates={"owner": "iceberg"})
+```
+
+Finally, drop the namespace (if you want!)
+
+```python
+# Drop a namespace
+catalog.drop_namespace("docs_example")
+```
+
 ## Create a table
 
 To create a table from a catalog:
@@ -167,6 +185,17 @@ with catalog.create_table_transaction(identifier="docs_example.bids", schema=sch
     txn.set_properties(test_a="test_aa", test_b="test_b", test_c="test_c")
 ```
 
+## Register a table
+
+To register a table using existing metadata:
+
+```python
+catalog.register_table(
+    identifier="docs_example.bids",
+    metadata_location="s3://warehouse/path/to/metadata.json"
+)
+```
+
 ## Load a table
 
 There are two ways of reading an Iceberg table; through a catalog, and by pointing at the Iceberg metadata directly. Reading through a catalog is preferred, and directly pointing at the metadata is read-only.
@@ -216,6 +245,31 @@ catalog.table_exists("docs_example.bids")
 
 Returns `True` if the table already exists.
 
+## Rename a table
+
+To rename a table:
+
+```python
+catalog.rename_table(
+    from_identifier="docs_example.bids",
+    to_identifier="docs_example.bids_backup"
+)
+```
+
+## Drop a table
+
+To drop a table:
+
+```python
+catalog.drop_table("docs_example.bids")
+```
+
+To drop a table and purge all data and metadata files:
+
+```python
+catalog.purge_table("docs_example.bids")
+```
+
 ## Write to a table
 
 Reading and writing is being done using [Apache Arrow](https://arrow.apache.org/). Arrow is an in-memory columnar format for fast data interchange and in-memory analytics. Let's consider the following Arrow Table: