Bump min macOS version to 11.0

See #1634
diff --git a/README.md b/README.md
index 87d07a8..c77020f 100644
--- a/README.md
+++ b/README.md
@@ -55,8 +55,7 @@
 
 ### Mac OS X
 
-- For Intel-based Macs, macOS 10.13 or newer. For ARM64 M1 based Macs, macOS
-  11.0 or newer.
+- macOS 11.0 or newer.
 - `java`: For running closure compiler (optional).  After installing emscripten
   via emsdk, typing 'emcc --help' should pop up a OS X dialog "Java is not
   installed. To open java, you need a Java SE 6 runtime. Would you like to