Fix grammatical error in RFdiffusion3 documentation

Fixed typo, clarified enzyme design language.

Author: rclune

models/rfd3/docs/index.rst

@@ -1,9 +1,9 @@
 RFdiffusion3 Documentation
 ==========================
 
-RFdiffusion3 is a powerful protein design tool that operate on the atomic level to 
+RFdiffusion3 is a powerful protein design tool that operates on the atomic level to 
 study ligand-protein interactions, create nucleic acid-protein interfaces, and 
-design enzymes with specific catalytic activities. It is designed to be highly flexible and 
+design *de novo* enzymes. It is designed to be highly flexible and 
 user-friendly, making it suitable for a wide range of applications in computational biology and biochemistry.
 
 General
@@ -30,4 +30,4 @@ Examples
    sm_binder_design.md
    protein_binder_design.md
    symmetry.md
-   enzyme_design.md
+   enzyme_design.md