Added markup, fixed Arch repos, reordered entries

For better redability

docs/user-guide/install.md

@@ -8,17 +8,17 @@ See [developer section documentation](../devs/building/requirements.md) for how
 
 ## Installation from prebuilt packages
 
-The easiest way to install i2pd is by using precompiled packages and binaries.  
+The easiest way to install i2pd is by using precompiled packages and binaries.
 Go to the [latest release page](https://github.com/PurpleI2P/i2pd/releases/latest) and choose a file for your operating system.
 
 
 ## Windows
 
 Check for [latest release page](https://github.com/PurpleI2P/i2pd/releases/latest) and choose a file for your system architecture:
-* i2pd_*_win32_mingw.zip -- for x86 systems
+* `i2pd_*_win32_mingw.zip` -- for x86 systems
-* i2pd_*_win64_mingw.zip -- for x86_64 (x64) systems
+* `i2pd_*_win64_mingw.zip` -- for x86_64 (x64) systems
-* i2pd_*_winxp_mingw.zip -- Windows XP compatible build
+* `i2pd_*_winxp_mingw.zip` -- Windows XP compatible build
-* setup_i2pd_*.exe -- Installer with automatic detection of used system and correct extraction of a configuration files
+* `setup_i2pd_*.exe` -- Installer with automatic detection of used system and correct extraction of a configuration files
 
 
 ## Android
@@ -41,18 +41,36 @@ You can use our [prebuilt docker images](https://hub.docker.com/r/purplei2p/i2pd
     docker pull purplei2p/i2pd
 
 
-## Ubuntu
+## Linux
 
-You can install binary packages from the [latest release page](https://github.com/PurpleI2P/i2pd/releases/latest). 
+### Distro-agnostic GUI
 
-Alternatively, you can use [PPA repository](https://launchpad.net/~purplei2p/+archive/ubuntu/i2pd) or repository provided [below](#debian), run by PurpleI2P community member [R4SAS](https://twitter.com/i2pr4sas).
+You can install i2pd GUI from Flathub using `flatpak`:
 
-    sudo add-apt-repository ppa:purplei2p/i2pd
+    sudo apt install flatpak
-    sudo apt-get update
+    flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo
-    sudo apt-get install i2pd
+    flatpak install flathub website.i2pd.i2pd
+
+### Arch
+
+i2pd packages are available at Arch's [extra repository](https://archlinux.org/packages/extra/x86_64/i2pd/) for release version, and [AUR](https://aur.archlinux.org/packages/i2pd-git/) for nightly builds.
+
+You can download them by running 
+
+     pacman -S i2pd --noconfirm
+
+### Gentoo
+
+i2pd [has a working ebuild in the main gentoo repository](https://packages.gentoo.org/packages/net-vpn/i2pd). As of May 2018, the ebuild 
+is still listed as "unstable", and thus will request an exception in your package.keywords if you are using gentoo under the "stable" branch.
+To install i2pd, enter the command:
+    
+    emerge --ask net-vpn/i2pd
 
+If you use `gcc` to compile packages and would like to enable cmake's hardening features, use the `i2p-hardening` flag (recommended).
+If you intend to use the websocket server, enable the `websocket` flag.
 
-## Debian
+### Debian
 
 Look for Debian packages at the [latest release page](https://github.com/PurpleI2P/i2pd/releases/latest).
 
@@ -73,43 +91,35 @@ After that you can install i2pd as any other software package:
 
 Look for more information about Debian repository [here](https://repo.i2pd.xyz/.help/readme.html).
 
-## Fedora/CentOS
+### Fedora/CentOS
 
 You can install i2pd from [repository](https://copr.fedorainfracloud.org/coprs/supervillain/i2pd/) 
 run by PurpleI2P community member [villain](https://twitter.com/el_villano_loco) and maintained by [R4SAS](https://twitter.com/i2pr4sas).
 
-### Centos 7:
+#### Centos 7:
 
     curl -s https://copr.fedorainfracloud.org/coprs/supervillain/i2pd/repo/epel-7/supervillain-i2pd-epel-7.repo -o /etc/yum.repos.d/i2pd-epel-7.repo
     yum install epel-release -y
     yum install i2pd -y
     systemctl enable --now i2pd
 
-### Fedora:
+#### Fedora:
 
     dnf copr enable supervillain/i2pd
     dnf install i2pd -y
     systemctl enable --now i2pd
 
+### Ubuntu
 
-## Arch
+You can install binary packages from the [latest release page](https://github.com/PurpleI2P/i2pd/releases/latest). 
-
-i2pd packages are available at Arch's repository for [release version](https://archlinux.org/packages/community/x86_64/i2pd/), and AUR for
-[nightly builds](https://aur.archlinux.org/packages/i2pd-git/)
-
-## Gentoo
 
-i2pd [has a working ebuild in the main gentoo repository](https://packages.gentoo.org/packages/net-vpn/i2pd). As of May 2018, the ebuild 
+Alternatively, you can use [PPA repository](https://launchpad.net/~purplei2p/+archive/ubuntu/i2pd) or repository provided [below](#debian), run by PurpleI2P community member [R4SAS](https://twitter.com/i2pr4sas).
-is still listed as "unstable", and thus will request an exception in your package.keywords if you are using gentoo under the "stable" branch.
-To install i2pd, enter the command:
-    
-    emerge --ask net-vpn/i2pd
 
-If you use gcc to compile packages and would like to enable cmake's hardening features, use the i2p-hardening flag (recommended).
+    sudo add-apt-repository ppa:purplei2p/i2pd
-If you intend to use the websocket server, enable the websocket flag.
+    sudo apt-get update
+    sudo apt-get install i2pd
 
-FreeBSD
+## FreeBSD
--------
 
 You can install i2pd from [ports](https://www.freshports.org/security/i2pd/).
 
@@ -121,11 +131,3 @@ You can install i2pd from [brew](https://brew.sh/) package manager:
 
 or use statically precompiled binary from [latest release page](https://github.com/PurpleI2P/i2pd/releases/latest).
 
-GUI application
----------------
-
-You can install i2pd GUI from flatpak:
-
-    sudo apt install flatpak
-    flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo
-    flatpak install flathub website.i2pd.i2pd