Update flit instructions

Co-authored-by: Kathy Pippert <[email protected]>

Author: jorgepiloto

doc/source/library_description/packaging.rst

@@ -109,8 +109,8 @@ the `pyansys template`_.
 Flit
 ^^^^
 
-It is a modern and lightweight build system. Using this tool requires
-developers to manage virtual environments by their own, that is:
+Flit is a modern and lightweight build system that requires developers
+to manage virtual environments on their own. Developers must:
 
 * Create a virtual environment and activate it.
 * Install the package in editable mode.