📝 docs: add Methods type documentation (sketch)

Author: Mat Dudek

docs/complex-types/methods.md

@@ -0,0 +1,41 @@
+# methods
+
+In this section we will explore 🚀 all nooks and crannies behind methods types.
+
+
+
+Diving into `methods.ts` we have these three imports
+
+```ts
+import { EntitySchema } from "./data" // Record<string, any>
+import { SyncKey } from "./sync" // Opaque<string, "sync-key">
+import { Except } from "type-fest" // Create a type from an object type without certain keys.
+```
+
+## Methods
+
+```ts
+export type Methods<TSchema extends EntitySchema> = Record<
+  string, // keys
+  (this: TSchema, ...args: any[]) => any // values
+>
+```
+
+`Methods<TSchema>`: This is a generic type called `Methods`. It takes a type parameter `TSchema`, which is expected to extend the `EntitySchema`.<br/>
+This means that `Methods` is a reusable type where we can use it for different EntityType. (dunno if I should explain this @TODO)
+
+
+```ts
+Record<string, ...>
+```
+This denotes as an 	__*object*__ type where keys are `strings`. Pretty logic, methods must be somehow named.
+
+```ts
+(this: TSchema, ...args: any[]) => any
+```
+This is the type of values in the __*object*__.<br/>
+It indicates a function that takes Ż
+ - `this` of type `TSchema` (the entity schema) as its first parameter. (We need to have an access to the object with data inside a function)
+ - `..args: any[]` means any number of arguments of any type (`rest syntax`)
+
+