Improve UnnamedVariable documentation

PiperOrigin-RevId: 960906256

core/src/main/java/com/google/errorprone/bugpatterns/UnnamedVariable.java

diff --git a/core/src/main/java/com/google/errorprone/bugpatterns/UnnamedVariable.java b/core/src/main/java/com/google/errorprone/bugpatterns/UnnamedVariable.java
index a14525f..09ea01f 100644
--- a/core/src/main/java/com/google/errorprone/bugpatterns/UnnamedVariable.java
+++ b/core/src/main/java/com/google/errorprone/bugpatterns/UnnamedVariable.java
@@ -51,7 +51,7 @@
 
 /** A bug pattern that suggests renaming unused variables to {@code var _}. */
 @BugPattern(
-    summary = "Consider renaming unused variables and lambda parameters to _",
+    summary = "Consider renaming unused variables and lambda parameters to `_`",
     severity = WARNING)
 public final class UnnamedVariable extends BugChecker implements CompilationUnitTreeMatcher {
 

docs/bugpattern/UnnamedVariable.md

diff --git a/docs/bugpattern/UnnamedVariable.md b/docs/bugpattern/UnnamedVariable.md
new file mode 100644
index 0000000..30b5142
--- /dev/null
+++ b/docs/bugpattern/UnnamedVariable.md
@@ -0,0 +1,2 @@
+Prefer using an unnamed variable (`_`) to denote variables and patterns that are
+intentionally unused.