doc: add LEDE/OpenWRT build instructions

Signed-off-by: Lucian Cristian <lucian.cristian@gmail.com>

doc/Building_FRR_for_LEDE-OpenWRT.md

@@ -0,0 +1,96 @@
+Building FRR for OpenWRT/LEDE from Git Source
+===============================================
+
+- for the moment because of cross compile problems, master is not supported,
+  only upto 3.0
+- LDP can't be built because of missing Perl-XML-LibXML in OpenWRT/LEDE tree
+
+Prepare build environment
+-------------------------
+
+https://lede-project.org/docs/guide-developer/install-buildsystem
+
+for
+
+Ubuntu 12.04LTS:
+
+    sudo apt-get install build-essential subversion git-core \
+       libncurses5-dev zlib1g-dev gawk flex quilt libssl-dev xsltproc \
+       libxml-parser-perl mercurial bzr ecj cvs unzip
+
+Ubuntu 64bit:
+
+    sudo apt-get install build-essential subversion libncurses5-dev zlib1g-dev \
+       gawk gcc-multilib flex git-core gettext libssl-dev
+
+Debian 8 Jessie:
+
+    sudo apt-get install build-essential libncurses5-dev gawk git subversion \
+       libssl-dev gettext unzip zlib1g-dev file python
+
+Debian 9 Stretch:
+
+    sudo apt-get install build-essential libncurses5-dev gawk git subversion \
+       libssl-dev gettext zlib1g-dev
+
+Centos x86-64 (some packages require EPEL):
+
+    yum install subversion binutils bzip2 gcc gcc-c++ gawk gettext flex \
+       ncurses-devel zlib-devel zlib-static make patch unzip glibc glibc-devel \
+       perl-ExtUtils-MakeMaker glibc-static quilt ncurses-libs sed sdcc bison \
+       intltool sharutils wget git-core openssl-devel xz
+
+Fedora 24 - 64Bit:
+
+    dnf install -y subversion binutils bzip2 gcc gcc-c++ gawk gettext git-core \
+       unzip ncurses-devel ncurses-compat-libs zlib-devel zlib-static make \
+       flex patch perl-ExtUtils-MakeMaker perl-Thread-Queue glibc glibc-devel \
+       glibc-static quilt sed sdcc intltool sharutils bison wget openssl-devel
+
+
+Get LEDE Sources (from Git)
+---------------------------
+
+LEDE and OpenWRT is planned to remerge and won't cover the similar OpenWRT build
+As normal user:
+    git clone https://git.lede-project.org/source.git lede
+    cd lede
+    ./scripts/feeds update -a
+    ./scripts/feeds install -a
+    cd feeds/routing
+    git pull origin pull/319/head
+    ln -s ../../../feeds/routing/frr/ ../../package/feeds/routing/
+    cd ../..
+    make menuconfig
+
+Select the needed target then select needed packages in
+Network -> Routing and Redirection -> frr, exit and save
+
+    make or make package/frr/compile
+
+It may be possible that on first build `make package/frr/compile` not to work
+and it may be needed to run a `make` for the entire build envronment, add V=s
+for debugging
+
+Work with sources
+-----------------
+
+To update the rc1 version or add other options, the Makefile is found in
+feeds/routing/frr
+
+edit:
+    PKG_VERSION:=
+    PKG_SOURCE_VERSION:=<git-hash>
+
+Usage
+-----
+
+Edit `/usr/sbin/frr.init` and add/remove the daemons name in section DAEMONS=
+or don't install unneded packages
+For example: zebra bgpd ldpd isisd nhrpd ospfd ospf6d pimd ripd ripngd
+
+### Enable the serivce
+ - service frr enable
+
+### Start the service
+ -  service frr start