Edits some docstrings

Author: FranciscoCanas

src/freeseer/frontend/controller/configuration/configuration.py

@@ -233,6 +233,9 @@ def list_plugin_instances(profile, category, plugin):
     """
     List existing plugin instances for the given profile, plugin category,
     and plugin type.
+
+    Raises:
+        HTTPError if profile, category, or plugin don't exist.
     """
     profile_instance = load_profile(profile)
     plugin_manager = PluginManager(profile_instance)
@@ -272,6 +275,9 @@ def create_plugin_instance(profile, category, plugin):
     """
     Create a new instance of a plugin for the given profile, plugin category,
     and plugin type.
+
+    Raises:
+        HTTPError: If profile does not exist.
     """
     uid = instantiate_plugin_config(profile, category, plugin)
     return {'id': uid}