fixed a typo in README.md file

[UV012]

Title

fix(docs): fix typo in README ("singe" -> "single")

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Description

Summary

Corrects a minor typo in README.md.

Changes

• File: README.md (Line 14)
• Fix: Changed singe to single

Before:

That first 50K of context riding along every singe message you send adds to cost over time, even if you're on some API.

After:

That first 50K of context riding along every single message you send adds to cost over time, even if you're on some API.