[rtems-lwip commit] README: Add build instruction

[Vijay Kumar Banerjee]

Module:    rtems-lwip
Branch:    main
Commit:    dc6830a6b785aa14976b2e395a6c54f418135d09
Changeset: http://git.rtems.org/rtems-lwip/commit/?id=dc6830a6b785aa14976b2e395a6c54f418135d09

Author:    Vijay Kumar Banerjee <vijay at rtems.org>
Date:      Thu Jul 21 13:15:31 2022 -0600

README: Add build instruction

---

 README | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/README b/README
index 91e42ae..99800bf 100644
--- a/README
+++ b/README
@@ -12,3 +12,21 @@ The sources presented here originate in one of several locations described by
 the ORIGIN.* files and whose license is described by the COPYING.* files.
 Commits adding such files should include the hash of the target repository if
 applicable.
+
+Installation Instructions
+-------------------------
+1. Populate the git submodules:
+
+```
+git submodule init
+git submodule update
+```
+2. Configure and build
+```
+./waf configure --prefix=INSTALL_PREFIX
+./waf
+./waf install
+```
+
+More `waf` arguments can be found by using:
+`./waf --help`