Add stock management section to inventory guide
More progress on shipping guide
Small improvements to readability - matches the wording in the spree_fancy README edited in commit https://github.com/j1mr10rd4n/spree_fancy/commit/fcd5905084ed49ccc185ec2f80d1f7d74fc55379
Added placeholder for decorators tutorial page
Merge pull request #90 from j1mr10rd4n/readability_improvements

Readability improvements
More WIP integrator changes
Guide Migrations
Add table styles
Finish porting old shipping content to new shipments guide
More shipments guide updates