pip install instructions

README.md

@@ -78,6 +78,7 @@
 To install a wheel from PyPI:
 
 ```sh
+pip install --upgrade "pip>=19.3" # manylinux2014 support
 pip install --upgrade orjson
 ```
 
@@ -81,11 +82,8 @@
 pip install --upgrade orjson
 ```
 
-To depend on orjson in a project:
-
-```txt
-orjson>=3,<4
-```
+Notice that Linux environments with a `pip` version shipped in 2018 or earlier
+must first upgrade `pip` to support `manylinux2014` wheels.
 
 To build a wheel, see [packaging](https://github.com/ijl/orjson#packaging).
 
@@ -89,7 +87,6 @@
 
 To build a wheel, see [packaging](https://github.com/ijl/orjson#packaging).
 
-
 ### Quickstart
 
 This is an example of serializing, with options specified, and deserializing: