[libgpiod][PATCH] README: list the development packages required to build the library

[Bartosz Golaszewski <brgl@bgdev.pl>]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

The error messages emitted by configure when either libtool, pkg-config
or autoconf-archive packages are missing on the host are not very clear
and seem to cause confusion among users building the project from
sources. List the required packages in the README.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 README | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/README b/README
index a6f24d1..a20e801 100644
--- a/README
+++ b/README
@@ -34,6 +34,11 @@ BUILDING
 This is a pretty standard autotools project. The core C library does not have
 any external dependencies other than the standard C library with GNU extensions.
 
+The build system requires autotools, autoconf-archive, libtool and pkg-config
+to be installed on the host system for the basic build. Development files for
+additional libraries may be required depending on selected options. The
+configure script will typically prompt the user for them clearly when missing.
+
 The command-line tools optionally depend on libedit for the interactive feature.
 
 To build the project (including command-line utilities) run:
-- 
2.43.0