Add warnings about 3.8 (resolves #4593) [ci skip]

README.md

@@ -104,6 +104,13 @@ For detailed installation instructions, see the
 [pip]: https://pypi.org/project/spacy/
 [conda]: https://anaconda.org/conda-forge/spacy
 
+> ⚠️ **Important note for Python 3.8:** We can't yet ship pre-compiled binary
+> wheels for spaCy that work on Python 3.8, as we're still waiting for our CI
+> providers and other tooling to support it. This means that in order to run
+> spaCy on Python 3.8, you'll need [a compiler installed](#source) and compile
+> the library and its Cython dependencies locally. If this is causing problems
+> for you, the easiest solution is to **use Python 3.7** in the meantime.
+
 ### pip
 
 Using pip, spaCy releases are available as source packages and binary wheels (as

website/docs/usage/index.md

@@ -20,6 +20,17 @@ available over [pip](https://pypi.python.org/pypi/spacy) and
 > possible, the new docs also include notes on features that have changed in
 > v2.0, and features that were introduced in the new version.
 
+<Infobox variant="warning" title="Important note for Python 3.8">
+
+We can't yet ship pre-compiled binary wheels for spaCy that work on Python 3.8,
+as we're still waiting for our CI providers and other tooling to support it.
+This means that in order to run spaCy on Python 3.8, you'll need
+[a compiler installed](#source) and compile the library and its Cython
+dependencies locally. If this is causing problems for you, the easiest solution
+is to **use Python 3.7** in the meantime.
+
+</Infobox>
+
 ## Quickstart {hidden="true"}
 
 import QuickstartInstall from 'widgets/quickstart-install.js'