docs: add OpenSSL dependency

Change-Id: I9739a444db03c29281c024bce9fd512ccbe2fe42
diff --git a/docs/INSTALL.rst b/docs/INSTALL.rst
index 900e839..f3c0ed6 100644
--- a/docs/INSTALL.rst
+++ b/docs/INSTALL.rst
@@ -40,6 +40,20 @@
 
           sudo port install protobuf-cpp
 
+-  openssl
+
+   On Ubuntu Linux:
+
+   ::
+
+          sudo apt-get install libssl-dev
+
+   On OS X with MacPorts:
+
+   ::
+
+          sudo port install openssl
+
 Build
 -----
 
@@ -54,11 +68,11 @@
 Refer to ``./waf –help`` for more options that can be used during the configure stage and
 how to properly configure NLSR.
 
-If your pkgconfig path is not set properly you can do following before running ``./waf
+If your pkgconfig path is not set properly you can do the following before running ``./waf
 configure``
 
 ::
 
     export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig/
     or
-    export PKG_CONFIG_PATH=/path/to/pkgconfig/in/your/machine
+    export PKG_CONFIG_PATH=/path/to/pkgconfig/on/your/machine