Add missing QLDocs

Author: owen-mc

go/ql/lib/semmle/go/security/StringBreakCustomizations.qll

@@ -106,12 +106,24 @@ module StringBreak {
     override Quote getQuote() { result = quote }
   }
 
+  /**
+   * A call to `strings.NewReplacer`.
+   */
   class StringsNewReplacerCall extends DataFlow::CallNode {
     StringsNewReplacerCall() { this.getTarget().hasQualifiedName("strings", "NewReplacer") }
 
+    /**
+     * Gets an argument to this call corresponding to a string that will be
+     * replaced.
+     */
     DataFlow::Node getAReplacedArgument() { exists(int n | n % 2 = 0 and result = getArgument(n)) }
   }
 
+  /**
+   * A configuration for tracking flow from a call to `strings.NewReplacer` to
+   * the receiver of a call to `strings.Replacer.Replace` or
+   * `strings.Replacer.WriteString`.
+   */
   class StringsNewReplacerConfiguration extends DataFlow2::Configuration {
     StringsNewReplacerConfiguration() { this = "StringsNewReplacerConfiguration" }