fix(api-reference): add missing Since and Types in Content collections

* See withastro/astro#7607 for the most recent
exported types
* See withastro/astro#6850 for `reference()`
* See `packages/astro/types/content.d.ts` for `schema` type (might
need a refactor)
* `getDataEntryById` is missing but since `getEntryBySlug` is
announced as deprecated I don't know if we should add it (so
no change here)

src/content/docs/en/reference/api-reference.mdx

@@ -1149,6 +1149,8 @@ Content collections offer APIs to configure and query your Markdown or MDX docum
 
 ### `defineCollection()`
 
+**Type:** `(input: CollectionConfig) => CollectionConfig`  
+
 `defineCollection()` is a utility to configure a collection in a `src/content/config.*` file.
 
 ```ts
@@ -1187,14 +1189,16 @@ This means collections **cannot** store a mix of content and data formats. You m
 
 #### `schema`
 
-**Type:** `TSchema extends ZodType`
+**Type:** `TSchema extends ZodType | (context: SchemaContext) => TSchema extends ZodType`
 
 `schema` is an optional Zod object to configure the type and shape of document frontmatter for a collection. Each value must use [a Zod validator](https://github.com/colinhacks/zod).
 
 [See the `Content Collection` guide](/en/guides/content-collections/#defining-a-collection-schema) for example usage.
 
 ### `reference()`
 
+<p><Since v="2.5.0" /></p>
+
 **Type:** `(collection: string) => ZodEffects<ZodString, { collection, id: string } | { collection, slug: string }>`
 
 The `reference()` function is used in the content config to define a relationship, or "reference," from one collection to another. This accepts a collection name and validates the entry identifier(s) specified in your content frontmatter or data file.
@@ -1395,6 +1399,8 @@ The `astro:content` module also exports the following types for use in your Astr
 
 #### `CollectionKey`
 
+<p><Since v="3.1.0" /></p>
+
 A string union of all collection names defined in your `src/content/config.*` file. This type can be useful when defining a generic function that accepts any collection name.
 
 ```ts
@@ -1407,10 +1413,14 @@ async function getCollection(collection: CollectionKey) {
 
 #### `ContentCollectionKey`
 
+<p><Since v="3.1.0" /></p>
+
 A string union of all the names of `type: 'content'` collections defined in your `src/content/config.*` file.
 
 #### `DataCollectionKey`
 
+<p><Since v="3.1.0" /></p>
+
 A string union of all the names of `type: 'data'` collection defined in your `src/content/config.*` file.
 
 #### `SchemaContext`