Polish previous release documents

Remove boldface and XXXes which were intended to be removed before
release.

doc/sphinx/whats-new/changes-7.1.rst

 .. _whatsnew_changes_7.1:
 
-%%%%%%%%%%%%%%%%%%%%%%%%%%
-Changes in Varnish **7.1**
-%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%
+Changes in Varnish 7.1
+%%%%%%%%%%%%%%%%%%%%%%
 
 For information about updating your current Varnish deployment to the
 new version, see :ref:`whatsnew_upgrading_7.1`.

doc/sphinx/whats-new/changes-7.2.rst

 .. _whatsnew_changes_7.2:
 
-%%%%%%%%%%%%%%%%%%%%%%%%%%
-Changes in Varnish **7.2**
-%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%
+Changes in Varnish 7.2
+%%%%%%%%%%%%%%%%%%%%%%
 
 For information about updating your current Varnish deployment to the
 new version, see :ref:`whatsnew_upgrading_7.2`.

doc/sphinx/whats-new/changes-7.3.rst

 .. _whatsnew_changes_7.3:
 
-%%%%%%%%%%%%%%%%%%%%%%%%%%
-Changes in Varnish **7.3**
-%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%
+Changes in Varnish 7.3
+%%%%%%%%%%%%%%%%%%%%%%
 
 For information about updating your current Varnish deployment to the
 new version, see :ref:`whatsnew_upgrading_7.3`.
@@ -19,8 +19,6 @@ varnishd
 Parameters
 ~~~~~~~~~~
 
-**XXX changes in -p parameters**
-
 There is a new parameter ``transit_buffer`` disabled by default to limit the
 amount of storage used for uncacheable responses. This is useful in situations
 where slow clients may consume large but uncacheable objects, to prevent them
@@ -76,8 +74,6 @@ Changes to VCL
 VCL variables
 ~~~~~~~~~~~~~
 
-**XXX new, deprecated or removed variables, or changed semantics**
-
 The variables ``req.xid``, ``bereq.xid`` and ``sess.xid`` are now integers
 instead of strings, but should remain usable without a VCL change in a string
 context.
@@ -119,13 +115,9 @@ after the probe times out.
 VMODs
 =====
 
-**XXX changes in the bundled VMODs**
-
 varnishlog
 ==========
 
-**XXX changes concerning varnishlog(1) and/or vsl(7)**
-
 The in-memory and on-disk format of VSL records changed to allow 64bit
 VXID numbers. The new binary format is **not compatible** with
 previous versions, and log dumps performed with a previous Varnish
@@ -141,21 +133,12 @@ find the client IP address.
 varnishadm
 ==========
 
-**XXX changes concerning varnishadm(1) and/or varnish-cli(7)**
-
 The ``debug.xid`` command generally used by ``varnishtest`` now sets
 up the next VXID directly.
 
-varnishstat
-===========
-
-**XXX changes concerning varnishstat(1) and/or varnish-counters(7)**
-
 varnishtest
 ===========
 
-**XXX changes concerning varnishtest(1) and/or vtc(7)**
-
 It is now possible to send special keys NPAGE, PPAGE, HOME and END to a
 process.
 
@@ -168,9 +151,6 @@ available for HTTP/2 checks.
 Changes for developers and VMOD authors
 =======================================
 
-**XXX changes concerning VRT, the public APIs, source code organization,
-builds etc.**
-
 There is a new convenience macro ``WS_TASK_ALLOC_OBJ()`` to allocate objects
 from the current tasks' workspace.
 

doc/sphinx/whats-new/upgrading-7.1.rst

 .. _whatsnew_upgrading_7.1:
 
-%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-Upgrading to Varnish **7.1**
-%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%
+Upgrading to Varnish 7.1
+%%%%%%%%%%%%%%%%%%%%%%%%
 
 varnishd
 ========

doc/sphinx/whats-new/upgrading-7.2.rst

 .. _whatsnew_upgrading_7.2:
 
-%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-Upgrading to Varnish **7.2**
-%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%
+Upgrading to Varnish 7.2
+%%%%%%%%%%%%%%%%%%%%%%%%
 
 varnishd
 ========

doc/sphinx/whats-new/upgrading-7.3.rst

 .. _whatsnew_upgrading_7.3:
 
-%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-Upgrading to Varnish **7.3**
-%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%
+Upgrading to Varnish 7.3
+%%%%%%%%%%%%%%%%%%%%%%%%
 
 New VSL format
 ==============