Remove [--editable] in install instructions.

Use -e only in docs targeted at contributors.

If a user copy-pastes  command line with [--editable], they will hit
an error. If they don't know the --editable option, we're giving them
a choice to make before they can move forwards, but this isn't a choice
they need to make right now.

CONTRIBUTING.md

@@ -124,6 +124,10 @@ Follow these steps to start contributing:
    $ pip install -e .[dev]
    ```
 
+   (If transformers was already installed in the virtual environment, remove
+   it with `pip uninstall transformers` before reinstalling it in editable
+   mode with the `-e` flag.)
+
    Right now, we need an unreleased version of `isort` to avoid a
    [bug](https://github.com/timothycrosley/isort/pull/1000):
 

README.md

@@ -93,14 +93,14 @@ When TensorFlow 2.0 and/or PyTorch has been installed, you can install from sour
 ```bash
 git clone https://github.com/huggingface/transformers
 cd transformers
-pip install [--editable] .
+pip install .
 ```
 
 When you update the repository, you should upgrade the transformers installation and its dependencies as follows:
 
 ```bash
 git pull
-pip install --upgrade [--editable] .
+pip install --upgrade .
 ```
 
 ### Run the examples

docs/README.md

@@ -4,7 +4,7 @@ To generate the documentation, you first have to build it. Several packages are
 you can install them with the following command, at the root of the code repository:
 
 ```bash
-pip install .[docs]
+pip install -e .[docs]
 ```
 
 ## Packages installed

docs/source/installation.md

@@ -17,7 +17,7 @@ To install from source, clone the repository and install with:
 ``` bash
 git clone https://github.com/huggingface/transformers.git
 cd transformers
-pip install [--editable] .
+pip install .
 ```
 
 ## Tests

examples/README.md

@@ -10,7 +10,7 @@ Execute the following steps in a new virtual environment:
 ```bash
 git clone https://github.com/huggingface/transformers
 cd transformers
-pip install [--editable] .
+pip install .
 pip install -r ./examples/requirements.txt
 ```
 

examples/pplm/README.md

@@ -15,7 +15,7 @@ Please check out the repo under uber-research for more information: https://gith
 
 ```bash
 git clone https://github.com/huggingface/transformers && cd transformers
-pip install [--editable] .
+pip install .
 pip install nltk torchtext # additional requirements.
 cd examples/pplm
 ```

examples/summarization/README.md

@@ -10,7 +10,7 @@ The model is loaded with the pre-trained weights for the abstractive summarizati
 
 ```
 git clone https://github.com/huggingface/transformers && cd transformers
-pip install [--editable] .
+pip install .
 pip install nltk py-rouge
 cd examples/summarization
 ```