fix broken links

README.md

@@ -10,7 +10,7 @@ If you have a comment or suggestion, please open an [Issue](https://github.com/d
 - [Verify YubiKey](#verify-yubikey)
 - [Download OS Image](#download-os-image)
 - [Required software](#required-software)
-  * [Debian/Ubuntu](#debian-ubuntu)
+  * [Debian/Ubuntu](#debianubuntu)
   * [Arch](#arch)
   * [RHEL7](#rhel7)
   * [OpenBSD](#openbsd)
@@ -19,7 +19,7 @@ If you have a comment or suggestion, please open an [Issue](https://github.com/d
 - [Entropy](#entropy)
 - [Creating keys](#creating-keys)
 - [Master key](#master-key)
-- [Sign with an existing key (optional)](#sign-with-an-existing-key--optional-)
+- [Sign with an existing key (optional)](#sign-with-an-existing-key-optional)
 - [Sub-keys](#sub-keys)
   * [Signing](#signing)
   * [Encryption](#encryption)
@@ -43,10 +43,10 @@ If you have a comment or suggestion, please open an [Issue](https://github.com/d
   * [Create configuration](#create-configuration)
   * [Replace agents](#replace-agents)
   * [Copy public key](#copy-public-key)
-  * [(Optional) Save public key for identity file configuration](#-optional--save-public-key-for-identity-file-configuration)
+  * [(Optional) Save public key for identity file configuration](#optional-save-public-key-for-identity-file-configuration)
   * [Connect with public key authentication](#connect-with-public-key-authentication)
   * [Import SSH keys](#import-ssh-keys)
-  * [Remote Machines (Agent Forwarding)](#remote-machines--agent-forwarding-)
+  * [Remote Machines (Agent Forwarding)](#remote-machines-agent-forwarding)
     + [Steps for older distributions](#steps-for-older-distributions)
   * [GitHub](#github)
   * [OpenBSD](#openbsd-1)