Clarify process diagrams

Assignments/project-grading.md

@@ -115,10 +115,10 @@ The allocation of the 10% credit will be as follows: Overview and manual will be
 ### * Technical Overview
 #### Satisfactory:
 * Technical Overview contains a description of any substantive changes to the existing Covey.Town codebase, and of the architecture of your new code.
-* It uses UML diagrams, CRC cards, state diagrams or other techniques that help describe the structure.
+* When appropriate, it uses diagrams and/or figures to illustrate a design (there is no requirement to use a specific tool or format for this - students often use lucidchart, draw.io, [mermaid](https://mermaid.live) or even hand-drawn diagrams).
 * It provides a well-reasoned rationale for why this is the "right" design. 
 * The document is at most 2 pages (fewer pages are absolutely acceptable, consider this a rough limit) 
-* 
+
 #### Meets minimum requirements:
 * Technical Overview includes a description of all major changes to the code compared to our existing Covey.Town codebase.
 * The document is at most 2 pages (fewer pages are absolutely acceptable, consider this a rough limit)