Improve ncm-cdp documentation

Fixes #255.
Document fetch_offset

Explain how fetch_offset and fetch_smear actually function.
Improve ncm-ccm documentation

Fixes #254
Add previously undocumented options

It is not clear whether base_url can actually be used as it does not seem
that it should be possible for profile to not be a valid URL.
Document default value of dbformat

It is applied in the perl code of ccm rather than the component.
Improve ncm-altlogrotate documentation

Fixes #251.
Remove duplicate over
Fix COMP in component name block
State that ccm context is currently unsupported
Explain why altlogrotate is named as such
Merge pull request #367 from jrha/more-documentation-fixes

More documentation fixes