Remove mention of nightly in pypi (apache#18635)

tools/pip/doc/CPU_ADDITIONAL.md

@@ -33,10 +33,3 @@ To install, use:
 ```bash
 pip install mxnet
 ```
-
-Nightly Builds
---------------
-To install the latest nightly build, use:
-```bash
-pip install --pre mxnet -f https://dist.mxnet.io/python
-```

tools/pip/doc/CU100_ADDITIONAL.md

@@ -35,10 +35,3 @@ To install:
 ```bash
 pip install mxnet-cu100
 ```
-
-Nightly Builds
---------------
-To install the latest nightly build, use:
-```bash
-pip install --pre mxnet-cu100 -f https://dist.mxnet.io/python
-```

tools/pip/doc/CU101_ADDITIONAL.md

@@ -35,10 +35,3 @@ To install:
 ```bash
 pip install mxnet-cu101
 ```
-
-Nightly Builds
---------------
-To install the latest nightly build, use:
-```bash
-pip install --pre mxnet-cu101 -f https://dist.mxnet.io/python
-```

tools/pip/doc/CU102_ADDITIONAL.md

@@ -35,10 +35,3 @@ To install:
 ```bash
 pip install mxnet-cu102
 ```
-
-Nightly Builds
---------------
-To install the latest nightly build, use:
-```bash
-pip install --pre mxnet-cu102 -f https://dist.mxnet.io/python
-```

tools/pip/doc/CU92_ADDITIONAL.md

@@ -34,10 +34,3 @@ To install:
 ```bash
 pip install mxnet-cu92
 ```
-
-Nightly Builds
---------------
-To install the latest nightly build, use:
-```bash
-pip install --pre mxnet-cu92 -f https://dist.mxnet.io/python
-```

tools/pip/doc/NATIVE_ADDITIONAL.md

@@ -35,10 +35,3 @@ To install:
 ```bash
 pip install mxnet-native
 ```
-
-Nightly Builds
---------------
-To install the latest nightly build, use:
-```bash
-pip install --pre mxnet-native -f https://dist.mxnet.io/python
-```