Update abi2.md delete 2nd "molecular mechanisms" section because it...

Update abi2.md delete 2nd "molecular mechanisms" section because it contradicts the 1st molecular mechanisms section

content/3.defense-systems/abi2.md

@@ -39,9 +39,6 @@ Here is an example found in the RefSeq database:
 
 The Abi2 system in *Veillonella parvula* (GCF_002005185.1, NZ_CP019721) is composed of 1 protein: Abi_2 (WP_077707938.1) 
 
-## Molecular mechanisms
-As far as we are aware, the molecular mechanisms remain unclear.
-
 ## Distribution of the system among prokaryotes
 
 ::article-system-distribution-plot