readme: create userland multithread section

README.adoc

@@ -965,7 +965,7 @@ Notable userland content included / moving into this repository includes:
 
 ==== Userland setup getting started
 
-There are several ways to run our userland content, notably:
+There are several ways to run our <<userland-content>>, notably:
 
 * natively on the host as shown at: <<userland-setup-getting-started-natively>>
 +
@@ -11792,12 +11792,12 @@ One "downside" of glibc is that it exercises much more kernel functionality on i
 
 This section contains userland content, such as <<c>>, <<cpp>> and <<posix>> examples.
 
+Getting started at: <<userland-setup>>
+
 Userland assembly content is located at: <<userland-assembly>>. It was split from this section basically becase we were hitting the HTML `h6` limit, stupid web :-)
 
 This content makes up the bulk of the link:userland/[] directory.
 
-Getting started at: <<userland-setup>>
-
 The quickest way to run the arch agnostic examples, which comprise the majority of the examples, is natively with: <<userland-setup-getting-started-natively>>
 
 This section was originally moved in here from: https://github.com/cirosantilli/cpp-cheat
@@ -11864,6 +11864,10 @@ Programs under link:userland/cpp/[] are examples of https://en.wikipedia.org/wik
 
 * link:userland/cpp/empty.cpp[]
 * link:userland/cpp/hello.cpp[]
+
+[[cpp-multithreading]]
+==== C++ multithreading
+
 * `<atomic>`: <<cpp17>> 32 "Atomic operations library"
 ** link:userland/cpp/atomic.cpp[]
 
@@ -11906,6 +11910,14 @@ getconf -a
 
 `getconf` is also specified by POSIX at: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/getconf.html but not the `-a` option which shows all configurations.
 
+=== Userland multithreading
+
+The following sections are related to multithreading in userland:
+
+* <cpp-multithreading>
+* <<x86-thread-synchronization-primitives>>
+* <<arm-lse>>
+
 == Userland assembly
 
 Programs under `userland/arch/<arch>/` are examples of userland assembly programming.
@@ -13228,7 +13240,9 @@ TODO We didn't manage to find a working ARM analogue to <<x86-rdtsc-instruction>
 * https://stackoverflow.com/questions/31620375/arm-cortex-a7-returning-pmccntr-0-in-kernel-mode-and-illegal-instruction-in-u/31649809#31649809
 * https://blog.regehr.org/archives/794
 
-=== x86 LOCK prefix
+=== x86 thread synchronization primitives
+
+==== x86 LOCK prefix
 
 Inline assembly example at: link:userland/cpp/atomic.cpp[]