Format and fix dead links in how-it-works doc

Author: graygilmore

packages/theme-graph/docs/how-it-works.md

@@ -3,8 +3,8 @@
 ## Table of contents
 
 1. [What it looks like](#what-it-looks-like)
-1. [Concepts overview](#concepts-overview)
-2. [Algorithm overview](#algorithm-overview)
+1. [Concepts overview](#concepts)
+1. [Algorithm overview](#algorithm-overview)
 
 ## What it looks like
 
@@ -18,42 +18,47 @@ It's a web of modules and links between them.
 
 A **Graph** is a set of Nodes and Edges.
 
-A **Theme Graph** is a set of *Modules* (nodes) and *References* (edges) defined by an array of *Entry Points*. It has these properties:
+A **Theme Graph** is a set of _Modules_ (nodes) and _References_ (edges) defined by an array of _Entry Points_. It has these properties:
+
 - `rootUri` - root of the theme, e.g. `file:/path/to/theme`
 - `entryPoints` - array of modules that define the theme (all templates and sections)
 - `modules` - all the modules in the theme indexed by URI
 
 A **Module** is an object that represents a theme file. It has these properties:
+
 - `uri` - module identifier, e.g. `file:/path/to/theme/snippets/file.liquid`
 - `type` - e.g. `liquid`, `json`, `javascript`, `css`.
 - `kind` - e.g. `block`, `section`, `snippet`, `template`, etc.
-- `references` - array of *References* that point to this module.
-- `dependencies` - array of *References* that this module depends on.
+- `references` - array of _References_ that point to this module.
+- `dependencies` - array of _References_ that this module depends on.
 
 A **Reference** is an object that defines a link between two modules. It has these properties:
+
 - `source` - a `uri` and `range` that defines which module depends on an other and _where_ in the source file,
 - `target` - a `uri` and `range` that defines which module is being dependended on and optionally what is being depended on in that file,
 - `type` - one of the following:
   - `direct` - the file can't exist without the other, e.g. `{% render 'child' %}`
   - `preset` - the file has a preset that depends on an other file, e.g. a section that has a preset that includes `group` and `text` blocks.
   - `indirect` - the file loosely depends on the other, but not explicilty. e.g. when a file accepts all public theme blocks (`"type": "@theme"`))
 
-
 ## Algorithm overview
 
 To build the graph, we _traverse_ each module in the set of entry points.
 
 When we _traverse_ a module, we do the following:
+
 - if the module was already visited, we return early, else
 - we extract dependencies from the module's AST, then
 - we _bind_ the module with its dependent modules, then
 - we _traverse_ the dependent modules (it's a recursive algorithm).
 
 When we _bind_ a parent module with a child module, we do the following:
+
 - we add the child module to the parent's dependencies,
 - we add the parent module to the child's references
 
 In pseudo code, it looks a bit like this:
+
 ```
 INPUT rootUri
 OUTPUT graph