Remove redundant noEmits, update comments

@ember/library-tsconfig/tsconfig.json

@@ -61,27 +61,20 @@
     // to a decision on what they want their types to be.
     "noEmitOnError": false,
 
-    // We use Babel for emitting runtime code, because it's very important that
-    // we always and only use the same transpiler for non-stable features, in
-    // particular decorators. If you were to change this to `true`, it could
-    // lead to accidentally generating code with `tsc` instead of Babel, and
-    // could thereby result in broken code at runtime.
-    "noEmit": true,
-
     // Ember makes heavy use of decorators; TS does not support them at all
     // without this flag.
     "experimentalDecorators": true,
 
-    // We don't use TS for compilation, only for generating declarations. So we
-    // enable declarations and declaration maps (which, when developing a
-    // library in an IDE, are useful for ctrl-clicking through to the actual
-    // source code rather than the `.d.ts` file), but we do not enable source
-    // maps, since those will be handled separately in the compilation step,
-    // e.g. via `rollup` and `@babel/plugin-transform-typescript`.
+    // We use Babel for compiling runtime JavaScript, so TS needs to emit *only*
+    // declarations and declaration maps (which, when developing a library in an
+    // IDE, are useful for ctrl-clicking through to the actual source code
+    // rather than the `.d.ts` file).
     "declaration": true,
     "declarationMap": true,
     "emitDeclarationOnly": true,
-    // Required for emitDeclarationOnly to actually emit declarations
+    // This is the default, but is being included here for clarity
+    // it *may not* be set to true in any consumer of this base tsconfig,
+    // else declarations will not emit.
     "noEmit": false,
 
     // Don't implicitly pull in declarations from `@types` packages unless we