Update percona-ext.md (#673)

Fixed broken link for pg_tde github

Co-authored-by: Anastasia Alexandrova <[email protected]>

docs/percona-ext.md

@@ -16,7 +16,9 @@ A query performance monitoring tool for PostgreSQL that brings more insight and
 
 An open-source extension designed to enhance PostgreSQL’s security by encrypting data files on disk. The encryption is transparent for users allowing them to access and manipulate the data and not to worry about the encryption process.
 
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 [pg_tde documentation :octicons-link-external-16:](https://percona.github.io/pg_tde/main/index.html){.md-button}
 
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