Add docs on generating schemas

docs/3-generating.md

@@ -7,4 +7,19 @@ permalink: /generating/
 
 # Generating Schemas
 
-Using the `schema_for!` macro, and `gen` module...
+The easiest way to generate a schema for a type that implements is to use the [`schema_for!` macro](https://docs.rs/schemars/latest/schemars/macro.schema_for.html), like so:
+```rust
+let my_schema = schema_for!(MyStruct);
+```
+
+This will create a schema that conforms to [JSON Schema Draft 7](https://json-schema.org/specification-links.html#draft-7), but this is liable to change in a future version of Schemars if support for other JSON Schema versions is added.
+
+If you want more control over how the schema is generated, you can use the [`gen` module](https://docs.rs/schemars/latest/schemars/gen/). There are two main types in this module:
+* [`SchemaSettings`](https://docs.rs/schemars/0.6.1/schemars/gen/struct.SchemaSettings.html), which defines what JSON Schema features should be used when generating schemas (for example, how `Option`s should be represented).
+* [`SchemaGenerator`](https://docs.rs/schemars/0.6.1/schemars/gen/struct.SchemaGenerator.html), which manages the generation of a schema document.
+
+See the API documentation for more info on how to use those types for custom schema generation.
+
+<!-- TODO: 
+create and link to example
+-->

docs/404.html

@@ -2,6 +2,7 @@
 permalink: /404
 layout: default
 nav_exclude: true
+title: Not Found
 ---
 
 <style type="text/css" media="screen">

schemars/src/gen.rs

@@ -2,6 +2,9 @@ use crate::schema::*;
 use crate::{JsonSchema, Map};
 
 /// Settings to customize how Schemas are generated.
+/// 
+/// The default settings currently conform to [JSON Schema Draft 7](https://json-schema.org/specification-links.html#draft-7), but this is liable to change in a future version of Schemars if support for other JSON Schema versions is added.
+/// If you require your generated schemas to conform to draft 7, consider using the [`draft07`](#method.draft07) method.
 #[derive(Debug, PartialEq, Clone)]
 pub struct SchemaSettings {
     /// If `true`, schemas for [`Option<T>`](Option) will include a `nullable` property.
@@ -33,7 +36,7 @@ pub struct SchemaSettings {
 pub enum BoolSchemas {
     /// `Bool` schemas may be used.
     Enabled,
-    /// `Bool` schemas may only be used in a schema's [`additionalProperties`](../sschema/struct.ObjectValidation.html#structfield.additional_properties) field.
+    /// `Bool` schemas may only be used in a schema's [`additionalProperties`](../schema/struct.ObjectValidation.html#structfield.additional_properties) field.
     AdditionalPropertiesOnly,
     /// `Bool` schemas will never be used.
     Disabled,