TLSchema readme (#1506)

This PR updates the TLSchema readme to remove reference to scripts which
are no longer present.

### Change Type

- [x] `documentation` — Changes to the documentation only (will not
publish a new version)

packages/tlschema/README.md

@@ -1,6 +1,6 @@
 # @tldraw/tlschema
 
-This package houses type definitions, schema migrations, and other type metadata for any persisted data in tldraw.
+This package houses type definitions, schema migrations, and other type metadata for the tldraw editor's default persisted data.
 
 There are three main kinds of types:
 
@@ -16,49 +16,9 @@ There are three main kinds of types:
 
   These are subtypes of the root TLAsset record type. They allow specifying a unique name and custom props for a particular kind of asset.
 
-## Creating a new record type
-
-To create a new record type called, e.g. `TLBanana`, run
-
-```sh
-# Create the new file in ./records/TLBanana.ts
-yarn new-record TLBanana
-# Rebuild the index files to make sure it is exported
-yarn index
-```
-
-You may then customize your new blank `TLBanana` type!
-
-## Creating a new shape type
-
-To create a new shape type called, e.g. `TLMapboxShape`, run
-
-```sh
-# Create the new file in ./shapes/TLMapboxShape.ts
-yarn new-shape TLMapboxShape
-# Rebuild the index files to make sure it is exported
-yarn index
-```
-
-You may then customize your new blank `TLMapboxShape` type!
-
-## Creating a new asset type
-
-To create a new shape type called, e.g. `TLZipFileAsset`, run
-
-```sh
-# Create the new file in ./assets/TLZipFileAsset.ts
-yarn new-asset TLZipFileAsset
-# Rebuild the index files to make sure it is exported
-yarn index
-```
-
-You may then customize your new blank `TLZipFileAsset` type!
-
 # Adding migrations
 
-If you make any kind of change to any persisted data shape in this package, you must add migrations that are able
+If you make any kind of change to any persisted data shape in this package, you must add migrations that are able to convert old versions to new versions, and vice-versa.
-to convert old versions to new versions, and vice-versa.
 
 If you are making a change that affects the structure of a record, shape, or asset, update the migrations in the same file as the record, shape, or asset is defined.
 
@@ -71,7 +31,7 @@ In `TLShape.ts`
 
 ```diff
  const Versions = {
-   Initial: 1,
+   RemoveSomeProp: 1,
 +  AddOwnerId: 2,
  } as const
 ```
@@ -90,11 +50,9 @@ and then adding a migration:
 
 ```diff
  export const shapeTypeMigrations = defineMigrations({
-   // STEP 2: Update the current version to point to your latest version
    currentVersion: Versions.Initial,
    firstVersion: Versions.Initial,
    migrators: {
-     // STEP 3: Add an up+down migration for the new version here
 +    [Versions.AddOwnerId]: {
 +      // add ownerId property
 +      up: (shape) => ({...shape, ownerId: null}),