Merge pull request #18195 from mshabunin:linux-tutorial

Installation tutorials rework

* Doc: general installation, config reference, linux installation

* Doc: addressed review comments

* Minor fixes

samples/install/linux_quick_install_contrib.sh

@@ -0,0 +1,28 @@
+#!/bin/bash
+# This file contains documentation snippets for Linux installation tutorial
+if [ "$1" = "--check" ] ; then
+sudo()
+{
+    command $@
+}
+fi
+
+# [body]
+# Install minimal prerequisites (Ubuntu 18.04 as reference)
+sudo apt update && sudo apt install -y cmake g++ wget unzip
+
+# Download and unpack sources
+wget -O opencv.zip https://github.com/opencv/opencv/archive/master.zip
+wget -O opencv_contrib.zip https://github.com/opencv/opencv_contrib/archive/master.zip
+unzip opencv.zip
+unzip opencv_contrib.zip
+
+# Create build directory and switch into it
+mkdir -p build && cd build
+
+# Configure
+cmake -DOPENCV_EXTRA_MODULES_PATH=../opencv_contrib-master/modules ../opencv-master
+
+# Build
+cmake --build .
+# [body]