Docs: Example of multiple catalogs (#194)

* feat(docs): example of multiple catalogs defined in .pyiceberg.yaml

* more explicit example

* lint

Author: jayceslesar

mkdocs/docs/api.md

@@ -33,6 +33,22 @@ catalog:
     credential: t-1234:secret
 ```
 
+Note that multiple catalogs can be defined in the same `.pyiceberg.yaml`:
+
+```yaml
+catalog:
+  hive:
+    uri: thrift://127.0.0.1:9083
+    s3.endpoint: http://127.0.0.1:9000
+    s3.access-key-id: admin
+    s3.secret-access-key: password
+  rest:
+    uri: https://rest-server:8181/
+    warehouse: my-warehouse
+```
+
+and loaded in python by calling `load_catalog(name="hive")` and `load_catalog(name="rest")`.
+
 This information must be placed inside a file called `.pyiceberg.yaml` located either in the `$HOME` or `%USERPROFILE%` directory (depending on whether the operating system is Unix-based or Windows-based, respectively) or in the `$PYICEBERG_HOME` directory (if the corresponding environment variable is set).
 
 For more details on possible configurations refer to the [specific page](https://py.iceberg.apache.org/configuration/).