Make javadoc <p> style guide compliant

This led to confusion for an open source contributor about how to format
code. We don't want to be like, "do as I say, not as I do."

https://google.github.io/styleguide/javaguide.html#s7.1.2-javadoc-paragraphs
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=122589700

java/google/registry/model/registrar/Registrar.java

@@ -202,8 +202,8 @@ public class Registrar extends ImmutableObject implements Buildable, Jsonifiable
   /**
    * Registrar name. This is a distinct from the client identifier since there are no restrictions
    * on its length.
-   * <p>
-   * NB: We are assuming that this field is unique across all registrar entities. This is not
+   *
+   * <p>NB: We are assuming that this field is unique across all registrar entities. This is not
    * formally enforced in our datastore, but should be enforced by ICANN in that no two registrars
    * will be accredited with the same name.
    *