fix: U-Boot General Info: Update host dependency list

libgnutls28-dev provides gnutls/gnutls.h header which is required to
build u-boot. Without this package, the u-boot build fails.

Signed-off-by: Sai Sree Kartheek Adivi <[email protected]>

Author: sskartheekadivi

source/linux/Foundational_Components/U-Boot/UG-General-Info.rst

@@ -12,7 +12,7 @@ General Information
 
       sudo apt install git xz-utils build-essential autoconf flex bison libssl-dev bc libncurses-dev \
       python3 python3-setuptools python3-dev python3-yaml python3-jsonschema python3-pyelftools \
-      swig yamllint
+      swig yamllint libgnutls28-dev
 
 .. note::