docs: add alterer (#2014)

Again, forgot some docs, and added missing descriptions

docs/api/delta_table/delta_table_alterer.md

@@ -0,0 +1,11 @@
+---
+search:
+  boost: 10
+---
+
+
+# TableAlterer
+
+::: deltalake.table.TableAlterer
+    options:
+        show_root_heading: true

mkdocs.yml

@@ -67,6 +67,7 @@ nav:
       - api/delta_table/metadata.md
       - api/delta_table/delta_table_merger.md
       - api/delta_table/delta_table_optimizer.md
+      - api/delta_table/delta_table_alterer.md
     - api/schema.md
     - api/storage.md
     - api/catalog.md

python/deltalake/table.py

@@ -785,13 +785,22 @@ def update(
     def optimize(
         self,
     ) -> "TableOptimizer":
+        """Namespace for all table optimize related methods.
+
+        Returns:
+            TableOptimizer: TableOptimizer Object
+        """
         return TableOptimizer(self)
 
     @property
     def alter(
         self,
     ) -> "TableAlterer":
-        """Namespace for all table alter related methods"""
+        """Namespace for all table alter related methods.
+
+        Returns:
+            TableAlterer: TableAlterer Object
+        """
         return TableAlterer(self)
 
     def merge(