docs: update documentation for ecdsa and eddsa

[yelhousni]

Description

update documentation for ecdsa and eddsa, especially the constraints count in comments (see #1112).

Type of change

• This change requires a documentation update

How has this been tested?

N/A

How has this been benchmarked?

N/A

Checklist:

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• I did not modify files generated from templates
• golangci-lint does not output errors locally
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules