Fix typo in cargo-yank docs (#16656)

This fixes a (very small) typo in the docs for `cargo-yank`.
Specifically, since "unintentional SemVer breakages" is plural, the "an"
that was at the beginning of that sentence was incorrect.

### What does this PR try to resolve?

There wasn't an issue, just a very tiny typo

### How to test and review this PR?

Hopefully this shouldn't need any testing... it's just a change to a
markdown file
diff --git a/src/doc/man/cargo-yank.md b/src/doc/man/cargo-yank.md
index b4d549c..e8c28b7 100644
--- a/src/doc/man/cargo-yank.md
+++ b/src/doc/man/cargo-yank.md
@@ -51,7 +51,7 @@
 ### When to yank
 
 Crates should only be yanked in exceptional circumstances, for example, an
-accidental publish, an unintentional SemVer breakages, or a significantly
+accidental publish, unintentional SemVer breakages, or a significantly
 broken and unusable crate. In the case of security vulnerabilities, [RustSec]
 is typically a less disruptive mechanism to inform users and encourage them
 to upgrade, and avoids the possibility of significant downstream disruption
diff --git a/src/doc/man/generated_txt/cargo-yank.txt b/src/doc/man/generated_txt/cargo-yank.txt
index c4c6370..0be726f 100644
--- a/src/doc/man/generated_txt/cargo-yank.txt
+++ b/src/doc/man/generated_txt/cargo-yank.txt
@@ -55,7 +55,7 @@
 
    When to yank
        Crates should only be yanked in exceptional circumstances, for example,
-       an accidental publish, an unintentional SemVer breakages, or a
+       an accidental publish, unintentional SemVer breakages, or a
        significantly broken and unusable crate. In the case of security
        vulnerabilities, RustSec <https://rustsec.org/> is typically a less
        disruptive mechanism to inform users and encourage them to upgrade, and
diff --git a/src/doc/src/commands/cargo-yank.md b/src/doc/src/commands/cargo-yank.md
index f975704..18de084 100644
--- a/src/doc/src/commands/cargo-yank.md
+++ b/src/doc/src/commands/cargo-yank.md
@@ -51,7 +51,7 @@
 ### When to yank
 
 Crates should only be yanked in exceptional circumstances, for example, an
-accidental publish, an unintentional SemVer breakages, or a significantly
+accidental publish, unintentional SemVer breakages, or a significantly
 broken and unusable crate. In the case of security vulnerabilities, [RustSec]
 is typically a less disruptive mechanism to inform users and encourage them
 to upgrade, and avoids the possibility of significant downstream disruption
diff --git a/src/etc/man/cargo-yank.1 b/src/etc/man/cargo-yank.1
index 44dafed..a5b2d7d 100644
--- a/src/etc/man/cargo-yank.1
+++ b/src/etc/man/cargo-yank.1
@@ -82,7 +82,7 @@
 .sp
 .SS "When to yank"
 Crates should only be yanked in exceptional circumstances, for example, an
-accidental publish, an unintentional SemVer breakages, or a significantly
+accidental publish, unintentional SemVer breakages, or a significantly
 broken and unusable crate. In the case of security vulnerabilities, \fIRustSec\fR <https://rustsec.org/>
 is typically a less disruptive mechanism to inform users and encourage them
 to upgrade, and avoids the possibility of significant downstream disruption