[Security] Bump sshpk from 1.13.1 to 1.15.1 in /docs

[dependabot-preview]

Bumps sshpk from 1.13.1 to 1.15.1. This update includes security fixes.

Vulnerabilities fixed

Sourced from The Sonatype OSS Index.

CWE-400: Uncontrolled Resource Consumption ('Resource Exhaustion')
The software does not properly restrict the size or amount of resources that are requested or influenced by an actor, which can be used to consume more resources than intended.

Affected versions: <1.14.1

Sourced from The GitHub Vulnerability Alert Database.

CVE-2018-3737
See https://nvd.nist.gov/vuln/detail/CVE-2018-3737.

Affected versions: < 1.13.2

Sourced from The Node Security Working Group.

Denial of Service
sshpk is vulnerable to ReDoS when parsing crafted invalid public keys

Affected versions: <=1.13.1

Release notes

Sourced from sshpk's releases.

v1.14.1

• Remove all remaining usage of jodid25519 (abandoned dep)
• Add support for DNSSEC key format
• Add support for Ed25519 keys in PEM format (according to draft-curdle-pkix)
• Fixes for X.509 encoding issues (asn.1 NULLs in RSA certs, cert string type mangling)
• Performance issues parsing long SSH public keys

Commits

• 2ab4f2a md5 fingerprints not quite right TritonDataCenter/node-sshpk#56 md5 fingerprints not quite right
• 026ef47 stop using optional deps to fix webpack TritonDataCenter/node-sshpk#53 stop using optional deps to fix webpack
• 53e23fe Support PKCS#5 AES-256-CBC encrypted private keys TritonDataCenter/node-sshpk#50 Support PKCS#5 AES-256-CBC encrypted private keys
• 6b68d49 want API for accessing x509 extensions TritonDataCenter/node-sshpk#54 want API for accessing x509 extensions
• 1088992 Buffer no longer performs length check for hex strings in node v8.x  TritonDataCenter/node-sshpk#52 Buffer no longer performs length check for hex strings i...
• 6ec6f9d want support for more obscure DN OIDs TritonDataCenter/node-sshpk#38 want support for more obscure DN OIDs
• 1cc4c99 package.json repository does not point to Joyent TritonDataCenter/node-sshpk#51 package.json repository does not point to Joyent
• 175758a Use Buffer.(from|alloc) instead of deprecated Buffer API TritonDataCenter/node-sshpk#46 Use Buffer.(from|alloc) instead of deprecated Buffer API
• 6edb37c Release 1.14.0
• 46065d3 Performance issues parsing long SSH public keys TritonDataCenter/node-sshpk#44 Performance issues parsing long SSH public keys
• Additional commits viewable in compare view

Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting @dependabot rebase.

---

Note: This repo was added to Dependabot recently, so you'll receive a maximum of 5 PRs for your first few update runs. Once an update run creates fewer than 5 PRs we'll remove that limit.

You can always request more updates by clicking Bump now in your Dependabot dashboard.

Dependabot commands and options

You can trigger Dependabot actions by commenting on this PR:

• @dependabot rebase will rebase this PR
• @dependabot recreate will recreate this PR, overwriting any edits that have been made to it
• @dependabot merge will merge this PR after your CI passes on it
• @dependabot cancel merge will cancel a previously requested merge
• @dependabot reopen will reopen this PR if it is closed
• @dependabot ignore this [patch|minor|major] version will close this PR and stop Dependabot creating any more for this minor/major version (unless you reopen the PR or upgrade to it yourself)
• @dependabot ignore this dependency will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself)
• @dependabot use these labels will set the current labels as the default for future PRs for this repo and language
• @dependabot use these reviewers will set the current reviewers as the default for future PRs for this repo and language
• @dependabot use these assignees will set the current assignees as the default for future PRs for this repo and language
• @dependabot use this milestone will set the current milestone as the default for future PRs for this repo and language
• @dependabot badge me will comment on this PR with code to add a "Dependabot enabled" badge to your readme

Additionally, you can set the following in your Dependabot dashboard:

• Update frequency (including time of day and day of week)
• Automerge options (never/patch/minor, and dev/runtime dependencies)
• Pull request limits (per update run and/or open at any time)
• Out-of-range updates (receive only lockfile updates, if desired)
• Security updates (receive only security updates, if desired)

Finally, you can contact us by mentioning @dependabot.

[dependabot-preview]

Looks like sshpk is up-to-date now, so this is no longer needed.