Update CI to 2024.12 spec, update README

.appveyor.yml

@@ -33,6 +33,12 @@ branches:
     - /fix\/.*/
     - /pr\/.*/
 
+skip_commits:
+  files:
+    - LICENSE
+    - meta/*
+    - README.md
+
 matrix:
   fast_finish: false
   # Adding MAYFAIL to any matrix job allows it to fail but the build stays green:
@@ -64,38 +70,18 @@ environment:
       B2_CXXSTD: 14,17
       B2_TOOLSET: msvc-14.1
 
-    - FLAVOR: Visual Studio 2013
-      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
-      B2_TOOLSET: msvc-12.0
-
     - FLAVOR: cygwin (32-bit)
       APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
       ADDPATH: C:\cygwin\bin;
       B2_ADDRESS_MODEL: 32
       B2_CXXSTD: 11,14,1z
-      B2_THREADING: threadapi=pthread
       B2_TOOLSET: gcc
 
     - FLAVOR: cygwin (64-bit)
       APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
       ADDPATH: C:\cygwin64\bin;
       B2_ADDRESS_MODEL: 64
       B2_CXXSTD: 11,14,1z
-      B2_THREADING: threadapi=pthread
-      B2_TOOLSET: gcc
-
-    - FLAVOR: mingw32
-      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
-      B2_ADDRESS_MODEL: 32
-      ADDPATH: C:\mingw\bin;
-      B2_CXXSTD: 11,14,1z
-      B2_TOOLSET: gcc
-
-    - FLAVOR: mingw64
-      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
-      ADDPATH: C:\mingw-w64\x86_64-8.1.0-posix-seh-rt_v6-rev0\mingw64\bin;
-      B2_ADDRESS_MODEL: 64
-      B2_CXXSTD: 11,14,17,2a
       B2_TOOLSET: gcc
 
 install: