_content/security/vulndb: fix URLs

Change-Id: I5d3f80e2ea21b29aefd9a3e019463a269d3900a7
Reviewed-on: https://go-review.googlesource.com/c/website/+/410175
Reviewed-by: Jonathan Amsterdam <jba@google.com>
Reviewed-by: Julie Qiu <julieqiu@google.com>
diff --git a/_content/security/vulndb/index.md b/_content/security/vulndb/index.md
index 67e6b78..f2ec71e 100644
--- a/_content/security/vulndb/index.md
+++ b/_content/security/vulndb/index.md
@@ -25,18 +25,18 @@
 govulncheck and can be consumed by other clients.
 
 3. A **client library**
-([golang.org/x/vuln/client](https:/golang.org/x/vuln/client)), which reads data
+([golang.org/x/vuln/client](https://golang.org/x/vuln/client)), which reads data
 from the Go vulnerability database. This is also used by pkg.go.dev to surface
 vulnerabilities.
 
 4. A **vulncheck API**
-([golang.org/x/vuln/vulncheck](https:/golang.org/x/vuln/vulncheck)), which is
+([golang.org/x/vuln/vulncheck](https://golang.org/x/vuln/vulncheck)), which is
 used to find vulnerabilities affecting Go packages and perform static analysis.
 This API is made available for clients that do not want to run the govulncheck
 binary, such as VS Code Go.
 
 5. The **govulncheck command**
-([golang.org/x/vuln/cmd/govulncheck](https:/golang.org/x/vuln/cmd/govulncheck),
+([golang.org/x/vuln/cmd/govulncheck](https://golang.org/x/vuln/cmd/govulncheck),
 a wrapper around the vulncheck library for use on the command line.
 
 6. A **web portal** that presents information about vulnerabilities, hosted at