patch 8.2.2439: not easy to figure out what packages to get

Problem:    Not easy to figure out what packages to get when installing Vim on
            a new Ubuntu system.
Solution:   Mention explicit commands that are easy to follow.

src/INSTALL

@@ -39,13 +39,53 @@ version of Vim that is small and starts up quickly, see the Makefile for how
 to disable the GUI and X11.  If you don't have GUI libraries and/or X11, these
 features will be disabled automatically.
 
+To built Vim on Ubuntu from scratch on a clean system using git:
+	Install tools required to be able to get and build Vim:
+	% sudo apt install git
+	% sudo apt install make
+	% sudo apt install clang
+	
+	Build Vim with default features:
+	% git clone https://github.com/vim/vim.git
+	% cd vim/src
+	% make
+
+	Run tests to check there are no problems:
+	% make test
+
+	Install Vim in /usr/local:
+	% sudo make install
+
+	Add X windows clipboard support (also needed for GUI):
+	% sudo apt install libxt-dev
+	% make reconfig
+
+	Add GUI support (ignore compiler warnings):
+	% sudo apt install libgtk2.0-dev
+	% make reconfig
+
+	Add Python 3 support:
+	% sudo apt install libpython3-dev
+	Uncomment this line in Makefile:
+		"CONF_OPT_PYTHON3 = --enable-python3interp"
+	% make reconfig
+
+	Debugging:
+	% sudo apt install valgrind
+	Uncomment this line in Makefile:
+		CFLAGS = -g -Wall -Wextra -Wshadow -Wmissing-prototypes -Wunreachable-code -Wno-deprecated-declarations -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1
+	% make reconfig
+	% make test_{test-name}
+	See output in testdir/valgrind.test_{test-name}
+
+
 See the start of Makefile for more detailed instructions about how to compile
 Vim.
 
 If you need extra compiler and/or linker arguments, set $CFLAGS and/or $LIBS
 before starting configure.  Example:
 
-	env  CFLAGS=-I/usr/local/include  LIBS=-lm  make
+	env CFLAGS=-I/usr/local/include  LIBS=-lm  make
 
 This is only needed for things that configure doesn't offer a specific argument
 for or figures out by itself.  First try running configure without extra

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2439,
 /**/
     2438,
 /**/