Search notes:

include/config/auto.conf

include/config/auto.conf is a generated file which stores the config values («Kernel configuration») that were used to compile the kernel. These values are typically configured in .config, but can be overridden with make KCONFIG_CONFIG=….
This file is included from the main Makefile if need-config is defined.
Apparently, this file is updated with make sysconfig.

Usage

The content of the file is used for build tools to determine which config options are currently enabled or disabled.
A list of files that use auto.conf can be found with: 
grep -rlF include/config/auto.conf
It turns out that in most cases, this file is

Content

The content of the file looks like so: 
#
# Automatically generated file; DO NOT EDIT.
# Linux/x86 6.5.0-rc7 Kernel Configuration
#
CONFIG_RING_BUFFER=y
CONFIG_HAVE_ARCH_SECCOMP_FILTER=y
CONFIG_SND_PROC_FS=y
CONFIG_SCSI_DMA=y
CONFIG_TCP_MD5SIG=y
CONFIG_KERNEL_GZIP=y
CONFIG_CC_HAS_SANCOV_TRACE_PC=y
CONFIG_ARCH_WANT_OPTIMIZE_VMEMMAP=y
…

See also

include/config/auto.conf.cmd
scripts/setlocalversion suggests to run make prepare if include/config/auto.conf does not exist.
include/config/
include/generated/autoconf.h
scripts/kconfig/conf
The default value of KCONFIG_AUTOCONFIG is include/config/auto.conf

Index

Fatal error: Uncaught PDOException: SQLSTATE[HY000]: General error: 8 attempt to write a readonly database in /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php:78 Stack trace: #0 /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php(78): PDOStatement->execute(Array) #1 /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php(30): insert_webrequest_('/notes/Linux/ke...', 1738279106, '3.145.88.138', 'Mozilla/5.0 App...', NULL) #2 /home/httpd/vhosts/renenyffenegger.ch/httpsdocs/notes/Linux/kernel/source/include/config/auto_conf(89): insert_webrequest() #3 {main} thrown in /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php on line 78