Fix icon for CPython interoperability benefit (#20)

* Fix Icon for Interoperability with CPython

It seems icon for CPython is not available or does not work probably due to trademark

* Reduce content of benefit-6 Open source

Author: ubaidsk

content/benefits/benefit-4.md

@@ -1,5 +1,5 @@
 ---
 title: "Just-In-Time (JIT)"
-icon: "fa fa-cogs"
+icon: "fa fa-clock"
 ---
 LPython supports Just-in-time compilation which requires only decorating Python function with @lpython.

content/benefits/benefit-5.md

@@ -1,6 +1,6 @@
 ---
 title: "Interoperability with CPython"
-icon: "fa fa-python"
+icon: "fa fa-cogs"
 ---
 LPython offers seamless interoperability with CPython.
 One can easily call functions in CPython libraries

content/benefits/benefit-6.md

@@ -2,4 +2,4 @@
 title: "Open source"
 icon: "fas fa-code-branch"
 ---
-LPython, being an open-source project, enjoys the advantages of cost-effectiveness, transparency, community collaboration, flexibility, rapid bug resolution, enhanced security, sustainability, knowledge exchange, worldwide support.
+LPython, being an open-source project, enjoys the advantages of community collab, transparency, rapid bug resolution, enhanced security, knowledge exchange and more.