Fix Typos in Documentation Files

[cypherpepe]

This pull request fixes minor typographical errors in the following documentation files:

1. adrs/003_simple_trait_system.md

   • Corrected the phrase "Not that there is no Self" to "Note that there is no Self."

2. vscode-cairo/README.md

   • Fixed "All settings all under the cairo1.* section" to "All settings are under the cairo1.* section."

[reviewable-StarkWare]

This change is 

[orizi]

Reviewed 2 of 2 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @Arcticae, @Draggu, @mkaput, and @piotmag769)