add embed docs for modelfile

docs/modelfile.md

@@ -12,6 +12,7 @@ A model file is the blueprint to create and share models with Ollama.
   - [FROM (Required)](#from-required)
     - [Build from llama2](#build-from-llama2)
     - [Build from a bin file](#build-from-a-bin-file)
+  - [EMBED](#embed)
   - [PARAMETER](#parameter)
     - [Valid Parameters and Values](#valid-parameters-and-values)
   - [TEMPLATE](#template)
@@ -88,6 +89,15 @@ FROM ./ollama-model.bin
 
 This bin file location should be specified as an absolute path or relative to the Modelfile location.
 
+### EMBED
+
+The EMBED instruction is used to add embeddings of files to a model. This is useful for adding custom data that the model can reference when generating an answer.
+
+```
+FROM <model name>:<tag>
+EMBED <file path>
+```
+
 ### PARAMETER
 
 The `PARAMETER` instruction defines a parameter that can be set when the model is run.