[install.md]remove the gcc and gxx in hard (#1122)

* remove the gcc and gxx in hard

* Update install.md

* Create install.md

* Update install.md

docs/source/install.md

@@ -107,11 +107,11 @@ popd
 # use the "bash" command to make the conda environment works
 bash
 # create an conda virtual environment
-conda create -y -n tools/venv python=3.7
+conda create -y -p tools/venv python=3.7
 # Activate the conda virtual environment:
 conda activate tools/venv
 # Install the conda packags
-conda install -y -c conda-forge sox libsndfile swig bzip2 libflac bc gcc_linux-64=8.4.0 gxx_linux-64=8.4.0
+conda install -y -c conda-forge sox libsndfile swig bzip2 libflac bc
 ```
 ### Install PaddlePaddle
 For example, for CUDA 10.2, CuDNN7.5 install paddle 2.2.0:
@@ -121,7 +121,7 @@ python3 -m pip install paddlepaddle-gpu==2.2.0
 ```
 ### Get the Function for Developing PaddleSpeech
 ```bash
-pip install .[develop]
+pip install -e .[develop]
 ```
 ### Install the Kaldi (Optional)
 ```bash