doc: Make OS specific instructions as headers so they are linkable

When html page is generated, all headers are generated as links on
the page. It is useful to have OS specific instructions as a link
to share with people.

Change-Id: I78645131b1f0acbedcf11964a204a24c45b62cff
Signed-off-by: Anastasia Klimchuk <aklm@flashrom.org>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/81780
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi

doc/dev_guide/building_from_source.rst

@@ -47,8 +47,11 @@ Installing dependencies
     * No external dependencies (documentation should be build without fetching all of pypi)
     * No Javascript?
 
-* Linux
+Linux
+"""""
+
 * Debian / Ubuntu
+
   ::
 
       apt-get install -y \
@@ -56,6 +59,7 @@ Installing dependencies
       libcmocka-dev libpci-dev libusb-1.0-0-dev libftdi1-dev libjaylink-dev
 
 * ArchLinux / Manjaro
+
   ::
 
       pacman -S --noconfirm \
@@ -63,6 +67,7 @@ Installing dependencies
       pciutils libusb libftdi libjaylink
 
 * openSUSE / SUSE
+
   ::
 
       zypper install -y \
@@ -70,6 +75,7 @@ Installing dependencies
       libcmocka-devel pciutils-devel libusb-1_0-devel libftdi1-devel libjaylink-devel
 
 * NixOS / nixpkgs
+
   * There is a ``shell.nix`` under ``scripts/``
 
   ::
@@ -79,14 +85,18 @@ Installing dependencies
       cmocka pciutils libusb1 libftdi1 libjaylink
 
 * Alpine Linux
+
   ::
 
       apk add \
       build-base meson ninja pkgconf py3-sphinx \
       cmocka-dev pciutils-dev libusb-dev libjaylink-dev
 
-* Windows
+Windows
+"""""""
+
 * MSYS2
+
   Install `MSYS2 <https://www.msys2.org/>`_ and ensure it is `fully updated <https://www.msys2.org/docs/updating/>`_.
 
   * ``libpci`` is not available through the package manager and pci based programmer are not supported on Windows.
@@ -106,8 +116,11 @@ Installing dependencies
       mingw-w64-i686-gcc mingw-w64-i686-meson mingw-w64-i686-ninja mingw-w64-i686-pkg-config mingw-w64-i686-python-sphinx \
       mingw-w64-i686-cmocka mingw-w64-i686-libusb mingw-w64-i686-libftdi mingw-w64-i686-libjaylink-git
 
-* MacOS
+MacOS
+"""""
+
 * Homebrew
+
   * ``libpci`` is not available through the package manager
   * ``libjaylink`` is not available through the package manager
 
@@ -117,8 +130,11 @@ Installing dependencies
       meson ninja pkg-config sphinx-doc \
       libusb libftdi
 
-* BSD
+BSD
+"""
+
 * FreeBSD / DragonFlyBSD
+
   * ``libusb1`` is part of the system
   * ``libjaylink`` is not available through the package manager
 
@@ -129,6 +145,7 @@ Installing dependencies
       cmocka libpci libftdi1
 
 * OpenBSD
+
   * ``libjaylink`` is not available through the package manager
 
   ::
@@ -138,6 +155,7 @@ Installing dependencies
       cmocka pciutils libusb1 libftdi1
 
 * NetBSD
+
   * ``libjaylink`` is not available through the package manager
   * note: https://www.cambus.net/installing-ca-certificates-on-netbsd/
 
@@ -147,7 +165,9 @@ Installing dependencies
       meson ninja pkg-config py39-sphinx \
       cmocka pciutils libusb1 libftdi1
 
-* OpenIndiana (Illumos, Solaris, SunOS)
+OpenIndiana (Illumos, Solaris, SunOS)
+"""""""""""""""""""""""""""""""""""""
+
 * ``libpci`` missing, pciutils is build without it
 * ``libftdi1`` & ``libjaylink`` are not available through the package manager
 * TODO: replace ``build-essential`` with the default compiler
@@ -156,7 +176,9 @@ Installing dependencies
 
      pkg install build-essential meson ninja cmocka libusb-1
 
-* DJGPP-DOS
+DJGPP-DOS
+"""""""""
+
 * Get `DJGPP <https://www.delorie.com/djgpp/>`_
 * A great build script can be found `here <https://github.com/andrewwutw/build-djgpp>`_
 * Download the `pciutils <https://mj.ucw.cz/sw/pciutils/>`_ sources
@@ -181,7 +203,9 @@ Installing dependencies
 * To compile flashrom use the ``meson_cross/i586_djgpp_dos.txt`` cross-file
 * You will need `CWSDPMI.EXE <https://sandmann.dotster.com/cwsdpmi/>`_ to run flashrom
 
-* libpayload
+libpayload
+""""""""""
+
     .. todo:: Add building instructions for libpayload