file_write_read.c: move from cpp-cheat

Improve README C section with example tree.

README.adoc

@@ -11659,6 +11659,8 @@ 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.
 
+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>>
@@ -11671,14 +11673,30 @@ This section was originally moved in here from: https://github.com/cirosantilli/
 
 Programs under link:userland/c/[] are examples of link:https://en.wikipedia.org/wiki/ANSI_C[ANSI C] programming:
 
+* link:userland/c/hello.c[]
+* main` and environment
+** link:userland/c/return0.c[]
+** link:userland/c/return1.c[]
+** link:userland/c/return2.c[]
+** link:userland/c/exit0.c[]
+** link:userland/c/exit1.c[]
+** link:userland/c/exit2.c[]
+** link:userland/c/print_argv.c[]
 * Standard library
-** assert.h
+** `assert.h`
 *** link:userland/c/assert_fail.c[]
 ** `stdlib.h`
-*** Exit related
+*** exit
 **** link:userland/c/abort.c[]
-
-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 :-)
+*** malloc
+**** link:userland/c/out_of_memory.c[]
+** `stdio.h`
+*** link:userland/c/stderr.c[]
+*** link:userland/c/getchar.c[]
+*** File IO
+**** link:userland/c/file_write_read.c[]
+* Fun
+** link:userland/c/infinite_loop.c[]
 
 ==== GCC C extensions
 
@@ -13084,7 +13102,7 @@ Note how Sn is weirdly packed inside Dn, and Dn weirdly packed inside Qn, likely
 
 And you can't access the higher bytes at D16 or greater with Sn.
 
-===== ARM vadd instruction
+===== ARM VADD instruction
 
 * link:userland/arch/arm/vadd_scalar.S[]: see also: <<floating-point-assembly>>
 * link:userland/arch/arm/vadd_vector.S[]: see also: <<simd-assembly>>
@@ -13203,20 +13221,20 @@ link:userland/arch/aarch64/add_vector.S[]
 
 Good first instruction to learn SIMD: <<simd-assembly>>
 
-===== ARMv8 aarch64 fadd instruction
+===== ARMv8 aarch64 FADD instruction
 
 * link:userland/arch/aarch64/fadd_vector.S[]: see also: <<simd-assembly>>
 * link:userland/arch/aarch64/fadd_scalar.S[]: see also: <<floating-point-assembly>>
 
-====== ARM fadd vs vadd
+====== ARM FADD vs VADD
 
 It is very confusing, but `fadds` and `faddd` in Aarch32 are <<gnu-gas-assembler-arm-unified-syntax,pre-UAL>> for `vadd.f32` and `vadd.f64` which we use in this tutorial: <<arm-vadd-instruction>>
 
 The same goes for most ARMv7 mnemonics: `f*` is old, and `v*` is the newer better syntax.
 
-But then, in ARMv8, they decided to use <<armv8-aarch64-fadd-instruction>> as the main floating point add name, and get rid of `vadd`!
+But then, in ARMv8, they decided to use <<armv8-aarch64-fadd-instruction>> as the main floating point add name, and get rid of VADD!
 
-Also keep in mind that fused multiply add is `fmadd`.
+Also keep in mind that fused multiply add is FMADD.
 
 Examples at: <<simd-assembly>>