Fix typos in README files

[sky-coderay]

Description:
This pull request fixes the following typos and grammatical issues in the documentation:

1. Changed "Transfering" to "Transferring" in examples/bitswap-transfer/README.md.
2. Fixed "can can" to "can" in pinning/remote/client/openapi/README.md.

No functional code changes were made; only documentation updates.

Changelog:

• Not applicable ([skip changelog]).

Checklist:

• Verified that the changes are grammatical and do not alter the meaning of the text.
• All changes are limited to documentation files.
• Verified that formatting and styling match the surrounding text.
• No breaking changes introduced.

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