fix example for existing Protocol

Author: zzstoatzz

docs/embeddings.md

@@ -116,7 +116,7 @@ You can create your own embedding function to use with Chroma, it just needs to
 from chromadb import Documents, EmbeddingFunction, Embeddings
 
 class MyEmbeddingFunction(EmbeddingFunction):
-    def __call__(self, texts: Documents) -> Embeddings:
+    def __call__(self, input: Documents) -> Embeddings:
         # embed the documents somehow
         return embeddings
 ```