docs: make technical prose concrete

docs/cordis-tutorial/index.md

@@ -53,6 +53,6 @@ The examples use three TypeScript features beyond ordinary modern JavaScript:
 - **`import type { Context } from 'cordis'`** imports only type information. It vanishes at runtime, so a plugin file that needs `Context` solely for annotations adds no runtime dependency.
 - **Declaration merging** (`declare module 'cordis' { ... }`) adds your entries to interfaces that Cordis already declares — for example the type of a new `ctx.greeter` property or event name. It generates no runtime wiring; the plugin separately provides the service or emits the event. Chapter 3 shows the pattern in full.
 
-Chapter 5 also uses an `interface` to describe a configuration object's fields and a generic type such as `Schema<Config>` to say which object shape a schema validates. You can copy those declarations as shown; the surrounding text explains what each one connects.
+Chapter 5 also uses an `interface` to describe a configuration object's fields and a generic type such as `Schema<Config>` to say which object fields a schema validates. You can copy those declarations as shown; the surrounding text explains what each one connects.
 
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