merge revision(s) 4250d7c910fd67c0da07c6213901009330e3cd51,83f96642d2d74569cc38319d02d5922fac8f66b8,447feb0aa08e20cc5eeb8b3a6f881de261a2c9a2,1d80d703141f01383604022f9e8e53e10865197c,e271a3d4afc47e812b50fc9c50f6bf34d2d723a6,366e88e508de7c59d69906ad948cccd7979e932b,d825e34962540d345eb3c5a70eb264b415e915a5,4250d7c910fd67c0da07c6213901009330e3cd51,f9e43782995b1f77e7b10c79941bbbda15620e2a: [Backport #17723]

	autogen.sh: Added

	Currently it just runs "autoreconf --install"
	---
	 aclocal.m4 | 4 ++--
	 autogen.sh | 3 +++
	 2 files changed, 5 insertions(+), 2 deletions(-)
	 create mode 100755 autogen.sh

	autogen.sh: Allow AUTORECONF envvar to specify the autoreconf
	 executable

	---
	 autogen.sh | 2 +-
	 1 file changed, 1 insertion(+), 1 deletion(-)

	Improved autogen.sh

	* update in the source directory
	* make symbolic links instead of copies
	* forward the arguments to autoreconf as-is
	---
	 autogen.sh | 8 +++++++-
	 1 file changed, 7 insertions(+), 1 deletion(-)

	autogen.sh: Make it work with sh (not bash)

	---
	 autogen.sh | 2 +-
	 1 file changed, 1 insertion(+), 1 deletion(-)

	[DOC] Update README files to use autoreconf [ci skip]

	---
	 README.ja.md | 3 +--
	 README.md    | 3 +--
	 2 files changed, 2 insertions(+), 4 deletions(-)

	[DOC] Update README [ci skip]

	* Use `autogen.sh`.
	* The subversion repository is only for old versions, and
	  secondary now.
	* Moved long links to footnotes.
	---
	 README.ja.md | 22 +++++++++-------------
	 README.md    | 11 +++++++----
	 2 files changed, 16 insertions(+), 17 deletions(-)

	Use autogen.sh

	---
	 .github/workflows/baseruby.yml           | 2 +-
	 .github/workflows/check_dependencies.yml | 2 +-
	 .github/workflows/compilers.yml          | 2 +-
	 .github/workflows/macos.yml              | 2 +-
	 .github/workflows/mjit.yml               | 2 +-
	 .github/workflows/ubuntu.yml             | 2 +-
	 6 files changed, 6 insertions(+), 6 deletions(-)

	autogen.sh: Added

	Currently it just runs "autoreconf --install"
	---
	 aclocal.m4 | 4 ++--
	 autogen.sh | 3 +++
	 2 files changed, 5 insertions(+), 2 deletions(-)
	 create mode 100755 autogen.sh

	get rid of aclocal (#4280)

	---
	 aclocal.m4   | 47 -----------------------------------------------
	 configure.ac | 35 ++++++++++++++++++++++++++++++++++-
	 2 files changed, 34 insertions(+), 48 deletions(-)

1 files changed, 7 insertions, 5 deletions

diff --git a/README.md b/README.md
index 350b560905..bd7c7813a7 100644
--- a/README.md
+++ b/README.md
@@ -51,7 +51,8 @@ if you are a committer.
 
 ### Subversion
 
-Stable branches for older Ruby versions can be checked out with the following command:
+Stable branches for older Ruby versions can be checked out with also the
+following command:
 
     $ svn co https://svn.ruby-lang.org/repos/ruby/branches/ruby_2_6/ ruby
 
@@ -71,16 +72,17 @@ send the following phrase:
 
     subscribe
 
-in the mail body (not subject) to the address
-[ruby-talk-request@ruby-lang.org](mailto:ruby-talk-request@ruby-lang.org?subject=Join%20Ruby%20Mailing%20List&body=subscribe).
+in the mail body (not subject) to the address [ruby-talk-request@ruby-lang.org].
+
+[ruby-talk-request@ruby-lang.org]: mailto:ruby-talk-request@ruby-lang.org?subject=Join%20Ruby%20Mailing%20List&body=subscribe
 
 ## How to compile and install
 
 1.  If you want to use Microsoft Visual C++ to compile Ruby, read
     [win32/README.win32](win32/README.win32) instead of this document.
 
-2.  If `./configure` does not exist or is older than `configure.ac`, run
-    `autoconf` to (re)generate configure.
+2.  Run `./autogen.sh` to generate configure, when you build the source checked
+    out from the Git repository.
 
 3.  Run `./configure`, which will generate `config.h` and `Makefile`.