Fix link

Author: jlevy

README.md

@@ -39,7 +39,7 @@ but it has since moved to GitHub, where people more talented than the original a
 Scope:
 
 - This guide is both for beginners and the experienced. The goals are *breadth* (everything important), *specificity* (give concrete examples of the most common case), and *brevity* (avoid things that aren't essential or digressions you can easily look up elsewhere). Every tip is essential in some situation or significantly saves time over alternatives.
-- This is written for Linux, with the exception of the "[macOS only](#os-x-only)" and "[Windows only](#windows-only)" sections. Many of the other items apply or can be installed on other Unices or macOS (or even Cygwin).
+- This is written for Linux, with the exception of the "[macOS only](#macos-only)" and "[Windows only](#windows-only)" sections. Many of the other items apply or can be installed on other Unices or macOS (or even Cygwin).
 - The focus is on interactive Bash, though many tips apply to other shells and to general Bash scripting.
 - It includes both "standard" Unix commands as well as ones that require special package installs -- so long as they are important enough to merit inclusion.