Updated README with instructions to load models from third-party apps (…

…#417)

README.md

@@ -582,6 +582,33 @@ run `sudo make install`. The command manuals are also typeset as PDF
 files that you can download from our GitHub releases page. Lastly, most
 commands will display that information when passing the `--help` flag.
 
+## Running llamafile with models downloaded by third-party applications
+
+This section answers the question *"I already have a model downloaded locally by application X, can I use it with llamafile?"*. The general answer is "yes, as long as those models are locally stored in GGUF format" but its implementation can be more or less hacky depending on the application. A few examples (tested on a Mac) follow.
+
+### LM Studio
+[LM Studio](https://lmstudio.ai/) stores downloaded models in `~/.cache/lm-studio/models`, in subdirectories with the same name of the models (following HuggingFace's `account_name/model_name` format), with the same filename you saw when you chose to download the file.
+
+ So if you have downloaded e.g. the `llama-2-7b.Q2_K.gguf` file for `TheBloke/Llama-2-7B-GGUF`, you can run llamafile as follows:
+
+```
+cd ~/.cache/lm-studio/models/TheBloke/Llama-2-7B-GGUF
+llamafile -m llama-2-7b.Q2_K.gguf
+```
+
+### Ollama
+
+When you download a new model with [ollama](https://ollama.com), all its metadata will be stored in a manifest file under `~/.ollama/models/manifests/registry.ollama.ai/library/`. The directory and manifest file name are the model name as returned by `ollama list`. For instance, for `llama3:latest` the manifest file will be named `.ollama/models/manifests/registry.ollama.ai/library/llama3/latest`.
+
+The manifest maps each file related to the model (e.g. GGUF weights, license, prompt template, etc) to a sha256 digest. The digest corresponding to the element whose `mediaType` is `application/vnd.ollama.image.model` is the one referring to the model's GGUF file.
+
+Each sha256 digest is also used as a filename in the `~/.ollama/models/blobs` directory (if you look into that directory you'll see *only* those sha256-* filenames). This means you can directly run llamafile by passing the sha256 digest as the model filename. So if e.g. the `llama3:latest` GGUF file digest is `sha256-00e1317cbf74d901080d7100f57580ba8dd8de57203072dc6f668324ba545f29`, you can run llamafile as follows:
+
+```
+cd ~/.ollama/models/blobs
+llamafile -m sha256-00e1317cbf74d901080d7100f57580ba8dd8de57203072dc6f668324ba545f29
+```
+
 ## Technical details
 
 Here is a succinct overview of the tricks we used to create the fattest