Abandon Travis; GitHub Actions as forward path

.travis.yml

@@ -1,3 +1,4 @@
+# No longer used -- see README-autobuild.md
 arch:
   - amd64
   - ppc64le

README-autobuild.md

@@ -6,7 +6,7 @@ GitHub actions are fine for Linux/MacOS/Windows at https://github.com/johnkerl/m
 
 ## C implementation
 
-## Travis CI for non-Windows
+### Travis CI for non-Windows
 
 * Travis was in place for years now
 * As of May 2021 `travis-ci.org` is moving to `travis-ci.com`
@@ -15,24 +15,24 @@ GitHub actions are fine for Linux/MacOS/Windows at https://github.com/johnkerl/m
 * Also, almost all commits these days are on the Go code so trigger a build of the C code on each commit is not a good use of resources
 * In summary: Travis CI is not currently working, and isn't worth fixing
 
-## GitHub actions for non-Windows
+### GitHub actions for non-Windows
 
 * Incompatible with `autoconf` as described at https://www.preining.info/blog/2018/12/git-and-autotools-a-hate-relation/
 * In summary `autoconf` does not work with GitHub Actions, and this does not appear to be a forward path
 
-## Conclusion for non-Windows
+### Conclusion for non-Windows
 
-* For those builds which do involve C code -- until the Go port is complete -- I'll runs C makes manually.
+* For those rare commits which do involve C code -- until the Go port is complete -- I'll runs C makes manually.
 * For releases, I'll run them manually -- which is the current process [as defined here](https://miller.readthedocs.io/en/latest/build.html#creating-a-new-release-for-developers).
 
-## Windows builds
+### Windows builds
 
 This used:
 
 * [appveyor.yml](appveyor.yml)
-* https://ci.appveyor.com/project/johnkerl/miller.
+* https://ci.appveyor.com/project/johnkerl/miller
 * https://github.com/johnkerl/miller/settings/hooks
 
 Unfortunately, I understand next to nothing about what I'm doing here -- whenever the AppVeyor build breaks (and the Travis build doesn't) I end up googling for various things in the https://ci.appveyor.com/project/johnkerl/miller build-log output, then iteratively updating `appveyor.yml` until I can get a build again.
 
-As of May 2021 I've disabled Appveyor builds. Moving forward, for the C implementation I'll build Windows executables on a personal laptop and upload `mlr.exe` when I cut a release
+As of May 2021 I've disabled Appveyor builds. Moving forward, for the C implementation I'll build Windows executables on a personal laptop and upload `mlr.exe` when I cut a release.

appveyor.yml

@@ -1,3 +1,4 @@
+# No longer used -- see README-autobuild.md
 install:
   - set PATH=C:\msys64\usr\bin;%PATH%
   - bash -lc "curl -O http://repo.msys2.org/msys/x86_64/msys2-keyring-r21.b39fb11-1-any.pkg.tar.xz"

go/todo.txt

@@ -1,8 +1,6 @@
 ================================================================
 TOP OF LIST:
 
-* travis-ci.org -> travis-ci.com
-
 * mlr -k
   o c,go
   o various test cases