doc: use MongoDB 4.4

Change-Id: I05496fbdf582bf02ec4b3c8faadba02b88a54de8

Author: Guillaume-sousa

docs/mdcs-2.0-install-pypi.md

@@ -111,7 +111,7 @@
 ###	1. Install supporting applications on your host system.
 
 * Python 3.6.8: https://www.anaconda.com/distribution/ (choose python 3.x)
-* MongoDB 4.0.3: https://www.mongodb.com/download-center#community
+* MongoDB 4.4: https://www.mongodb.com/download-center#community
 * Redis 5.0: https://redis.io/download
 * Celery    : NOTE: This is installed below via `pip install`.
 * gettext   : This utility is necessary for supporting internationalization in MDCS 2.0 systems >= MDCS 2.0 beta2.