docs: add docs for engine, makeup for models docs

docs/docs/specs/engineering/engine.md

@@ -1,6 +1,59 @@
 ---
-title: Engine
+title: Engine Specifications
 slug: /specs/engine
 ---
 
-# Hello world
+:::caution
+
+Currently Under Development
+
+:::
+
+## Overview
+
+In the Jan application, engines serve as primary entities with the following capabilities:
+
+- Ability to add or remove engines via the installation of extensions.
+- Dependence on engines for conducting [inference](https://en.wikipedia.org/wiki/Inference_engine).
+
+## Folder Structure
+
+- Default parameters for engines are stored in JSON files located in the `/engines` folder.
+- These parameter files are named uniquely with `engine_id`.
+- Engines are referenced directly using `engine_id` in the `model.json` file.
+
+```yaml
+jan/
+    engines/
+        nitro.json
+        openai.json
+        .....
+```
+
+## Engine Default Parameter Files
+
+- Each inference engine requires default parameters to function in cases where user-provided parameters are absent.
+- These parameters are stored in JSON files, structured as simple key-value pairs.
+
+### Example
+
+Here is an example of an engine file for `engine_id` `nitro`:
+
+```js
+{
+    "llama_model_path": "/model/llama-2-7b-model.gguf",
+    "ctx_len": 512,
+    "ngl": 100,
+    "embedding": false,
+    "n_parallel": 1,
+    "cont_batching": false
+}
+```
+
+For detailed engine parameters, refer to: [Nitro's Model Settings](https://nitro.jan.ai/features/load-unload#table-of-parameters)
+
+## Adding an Engine
+
+- Engine parameter files are automatically generated upon installing an `inference-extension` in the Jan application.
+
+---

docs/docs/specs/engineering/models.md

@@ -64,7 +64,7 @@ Here's a standard example `model.json` for a GGUF model.
 "description": null,                // Defaults to null
 "state": enum[null, "downloading", "ready", "starting", "stopping", ...]
 "format": "ggufv3",                 // Defaults to "ggufv3"
-"engine_parameters": {              // Engine
+"engine_parameters": {              // Engine parameters inside model.json can override the value inside the base engine.json
     "ctx_len": 2048,
     "ngl": 100,
     "embedding": true,