Fix some docstrings

Author: brechtm

src/rinoh/font/__init__.py

@@ -155,7 +155,7 @@ class Typeface(Resource, dict):
     The fonts collected in a typeface differ in weight, width and/or slant.
 
     Args:
-        *fonts (:class:`Font`): the fonts that make up this typeface
+        fonts (:class:`Font`): the fonts that make up this typeface
 
     """
 

src/rinoh/structure.py

@@ -104,7 +104,7 @@ class Heading(StaticParagraph):
     """The title for a section
 
     Args:
-        title (StyledText): this heading's text
+        content (StyledText): this heading's text
 
     """
 

src/rinoh/template.py

@@ -553,7 +553,7 @@ class TemplateConfiguration(RuleSet):
         template (DocumentTemplateMeta or str): the document template to
             configure
         description (str): a short string describing this style sheet
-        **options: configuration values for the configuration attributes
+        options: configuration values for the configuration attributes
             defined by the document :attr:`template`
 
     """
@@ -707,7 +707,7 @@ class PartsList(AttributeType, list):
     """Stores the names of the document part templates making up a document
 
     Args:
-        *parts (list[str]): the names of the document parts
+        parts (list[str]): the names of the document parts
 
     """