Add links.txt

The file indicates where you can find kernel configurations.

config_files/links.txt

+######################################################
+#                                                    #
+# Some kernel configurations are available directly. #
+#                                                    #
+######################################################
+
+Alpine Linux:
+https://git.alpinelinux.org/cgit/aports/plain/main/linux-vanilla/config-vanilla.x86_64?h=3.8-stable
+https://git.alpinelinux.org/cgit/aports/plain/main/linux-vanilla/config-vanilla.x86_64
+
+Arch Linux:
+https://git.archlinux.org/svntogit/packages.git/plain/trunk/config?h=packages/linux
+https://git.archlinux.org/svntogit/packages.git/plain/trunk/config.x86_64?h=packages/linux-hardened
+
+Oracle Linux: Unbreakable Enterprise Kernel (UEK):
+https://raw.githubusercontent.com/oracle/linux-uek/uek5/master/uek-rpm/ol7/config-x86_64
+
+SUSE Linux Enterprise (SLE):
+https://kernel.opensuse.org/cgit/kernel-source/plain/config/x86_64/default?h=SLE15-SP1
+
+openSUSE:
+https://kernel.opensuse.org/cgit/kernel-source/plain/config/x86_64/default?h=openSUSE-42.3
+https://kernel.opensuse.org/cgit/kernel-source/plain/config/x86_64/default?h=stable
+https://kernel.opensuse.org/cgit/kernel-source/plain/config/x86_64/default
+
+Pentoo:
+https://github.com/pentoo/pentoo-livecd/tree/master/livecd/amd64/kernel