Add includable piece of markdown with all common attributes.

Include common attributes in most promise type page so that
attributes show up in the TOC; otherwise, users that don't
know about common attributes (or which ones are common) have
a hard time finding the documentation when looking in the
documentation of the promise type they are currently in.
Nest common attributes under header to make them dominate less.

Fix typo in hand(l)e.
filesize.cf doesn't have or require a preparation step.

Silence warning from generator.
Raw documentation for makerule.
Markdown format makerule documentation.

Also some light editing, including fixing of line endings.
Fix XML in env_spec example
Make reference to generic package_method a link
Merge pull request #309 from nickanderson/minor

Make reference to generic package_method a link
Link standard library documentation to relevant promise type
Document import syntax for individual library segments.
s/bodies/bundles for features and paths
Fix title for storage library
Annotate common attributes include to describe what common attributes are
Merge pull request #310 from nickanderson/annotate_common_attributes_include

Annotate common attributes Include to describe what common attributes are
Fix typos that break links
Section headers are used in links as they are