doc: Remove line breaks after <title>

This creates unnecessary rendering problem risks, and it's
inconsistent and gets copied around.

doc/src/sgml/features.sgml

@@ -419,9 +419,7 @@
    </sect2>
 
    <sect2 id="functions-xml-limits-postgresql">
-    <title>
-     Incidental limits of the implementation
-    </title>
+    <title>Incidental limits of the implementation</title>
 
     <para>
      This section concerns limits that are not inherent in the

doc/src/sgml/ref/createdb.sgml

@@ -31,9 +31,7 @@ PostgreSQL documentation
 
 
  <refsect1 id="r1-app-createdb-1">
-  <title>
-   Description
-  </title>
+  <title>Description</title>
   <para>
    <application>createdb</application> creates a new <productname>PostgreSQL</productname>
    database.

doc/src/sgml/ref/initdb.sgml

@@ -34,9 +34,7 @@ PostgreSQL documentation
  </refsynopsisdiv>
 
  <refsect1 id="r1-app-initdb-1">
-  <title>
-   Description
-  </title>
+  <title>Description</title>
   <para>
    <command>initdb</command> creates a new
    <productname>PostgreSQL</productname> database cluster.  A database

doc/src/sgml/ref/pg_basebackup.sgml

@@ -27,9 +27,7 @@ PostgreSQL documentation
  </refsynopsisdiv>
 
  <refsect1>
-  <title>
-   Description
-  </title>
+  <title>Description</title>
   <para>
    <application>pg_basebackup</application> is used to take base backups of
    a running <productname>PostgreSQL</productname> database cluster. These

doc/src/sgml/ref/pg_dump.sgml

@@ -33,9 +33,7 @@ PostgreSQL documentation
 
 
  <refsect1 id="pg-dump-description">
-  <title>
-   Description
-  </title>
+  <title>Description</title>
 
   <para>
    <application>pg_dump</application> is a utility for backing up a

doc/src/sgml/ref/pg_receivewal.sgml

@@ -27,9 +27,7 @@ PostgreSQL documentation
  </refsynopsisdiv>
 
  <refsect1>
-  <title>
-   Description
-  </title>
+  <title>Description</title>
   <para>
    <application>pg_receivewal</application> is used to stream the write-ahead log
    from a running <productname>PostgreSQL</productname> cluster. The write-ahead

doc/src/sgml/ref/pg_verifybackup.sgml

@@ -28,9 +28,7 @@ PostgreSQL documentation
  </refsynopsisdiv>
 
  <refsect1>
-  <title>
-   Description
-  </title>
+  <title>Description</title>
   <para>
    <application>pg_verifybackup</application> is used to check the
    integrity of a database cluster backup taken using

doc/src/sgml/xplang.sgml

@@ -62,9 +62,7 @@
    </para>
 
    <procedure>
-    <title>
-     Manual Procedural Language Installation
-    </title>
+    <title>Manual Procedural Language Installation</title>
 
     <para>
      A procedural language is installed in a database in five steps,