docs: clearify default behaviour of load_dotenv

closes #457

README.md

@@ -36,13 +36,13 @@ configurable via the environment:
 ```python
 from dotenv import load_dotenv
 
-load_dotenv()  # take environment variables from .env.
+load_dotenv()  # take environment variables
 
 # Code of your application, which uses environment variables (e.g. from `os.environ` or
 # `os.getenv`) as if they came from the actual environment.
 ```
 
-By default, `load_dotenv` doesn't override existing environment variables.
+By default, `load_dotenv` doesn't override existing environment variables and looks for a `.env` file in same directory as python script or searches for it incrementally higher up.
 
 To configure the development environment, add a `.env` in the root directory of your
 project:

src/dotenv/main.py

@@ -340,7 +340,9 @@ def load_dotenv(
         Bool: True if at least one environment variable is set else False
 
     If both `dotenv_path` and `stream` are `None`, `find_dotenv()` is used to find the
-    .env file.
+    .env file with it's default parameters. If you need to change the default parameters
+    of `find_dotenv()`, you can explicitly call `find_dotenv()` and pass the result
+    to this function as `dotenv_path`.
     """
     if dotenv_path is None and stream is None:
         dotenv_path = find_dotenv()