Update readme for compilers.

[skip ci]

README.adoc

@@ -14,11 +14,11 @@ file LICENSE.txt or copy at https://www.bfgroup.xyz/b2/LICENSE.txt)
 
 Continuously tested on:
 
-* FreeBSD Clang 10, 11, 12, 13, 14, 15, 16
+* FreeBSD Clang 10, 11, 12, 13, 14, 15, 16, 17
 * FreeBSD GCC 8, 9, 10, 11, 12, 13
-* Linux Clang 10, 11, 12, 13, 14, 15, 16
+* Linux Clang 10, 11, 12, 13, 14, 15, 16, 17
 * Linux GCC 9, 10, 11, 12, 13
-* macOS Xcode 11.7, 12.4, 12.5.1, 13.4.1, 14.0.1, 14.1, 14.2
+* macOS Xcode 11.7, 12.4, 12.5.1, 13.4.1, 14.0.1, 14.1, 14.2, 14.3.1, 15.0.1
 * Windows MinGW 8.1.0
 * Windows 2015, 2017, 2019, 2022
 * Windows MSYS2 MinGW64/32 Clang-16, MinGW64/32 GCC-13
@@ -34,7 +34,7 @@ image:https://img.shields.io/cirrus/github/bfgroup/b2?logo=cirrusci&label=main["
 image:https://img.shields.io/github/actions/workflow/status/bfgroup/b2/qemu_multiarch_linux.yml?logo=github["Ubuntu 22.04 GCC 11 (armhf, arm64, ppc64el)", link="https://github.com/bfgroup/b2/actions/workflows/qemu_multiarch_linux.yml"]
 image:https://img.shields.io/github/actions/workflow/status/bfgroup/b2/core_tests.yml?logo=github["Windows MSYS2 MinGW64/32 Clang-16, MinGW64/32 GCC-13", link="https://github.com/bfgroup/b2/actions/workflows/core_tests.yml"]
 
-NOTE: A C+\+11 capable compiler is needed to build the `b2` engine. But using
+NOTE: A {CPP}11 capable compiler is needed to build the `b2` engine. But using
 the `b2` engine and build system does not require C++11.
 
 == More