docs update with case study (#63)

* docs(manual): add introduction page

* docs(manual): rewrite getting started as guided first run

* docs(manual): rewrite writing specs as a folio tutorial

* docs(manual): document missing spec API in reference

* docs(manual): plain-language rewrite of runs page

* docs: real introductions on index pages and README

* fix(docs): sibling links from directory-style pages need ../

* fix(docs): correct sampling and restart-cost claims to match implementation

* docs: nav lists Introduction and Case study; roadmap points to milestone

* docs(manual): make getting started target the reader's own app, not Folio

* docs(manual): add Folio case study page

* docs: point manual navigation at the case study

* docs(readme): lead with the case study, fix roadmap link

* docs: roadmap links to milestone, sync clear-data default and cross-links

docs/development/index.md

@@ -6,7 +6,7 @@ title: Development
 
 - [Design principles](./design-principles/)
 - [Architecture](./architecture/)
-- v0.1.0 scope: [issue #4](https://github.com/priyanshujain/sanderling/issues/4)
+- v0.1.0 scope: [milestone #1](https://github.com/priyanshujain/sanderling/milestone/1)
 
 ## Building the docs site locally