Fix link syntax typo

Fix a missing parentheses in the markdown for a link caused by the URL
containing parentheses.

doc/security/password_storage.md

@@ -10,4 +10,4 @@ GitLab uses the [Devise](https://github.com/plataformatec/devise) authentication
 
 - **Hashing**: the [bcrypt](https://en.wikipedia.org/wiki/Bcrypt) hashing function is used to generate the hash of the provided password. This is a strong, industry-standard cryptographic hashing function.
 - **Stretching**: Password hashes are [stretched](https://en.wikipedia.org/wiki/Key_stretching) to harden against brute-force attacks. GitLab uses a streching factor of 10 by default.
-- **Salting**: A [cryptographic salt](https://en.wikipedia.org/wiki/Salt_(cryptography) is added to each password to harden against pre-computed hash and dictionary attacks. Each salt is randomly generated for each password, so that no two passwords share a salt to further increase security.
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+- **Salting**: A [cryptographic salt](https://en.wikipedia.org/wiki/Salt_(cryptography)) is added to each password to harden against pre-computed hash and dictionary attacks. Each salt is randomly generated for each password, so that no two passwords share a salt to further increase security.
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