logging.html.in: Kill useless spaces in <pre/>

The <pre/> section is rendered as-is on the page. That is, if all
the lines are prefixed with 4 spaces the rendered page will also
have them. Problem is if we put a box around such <pre/> because
the content might not fix into it.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>

docs/logging.html.in

@@ -102,8 +102,8 @@
        variables.</p>
     <p>The format for a filter is one of:</p>
     <pre>
-  x:name  (log message only)
-  x:+name (log message + stack trace)</pre>
+x:name  (log message only)
+x:+name (log message + stack trace)</pre>
     <p>where <code>name</code> is a string which is matched against
     the category given in the VIR_LOG_INIT() at the top of each
     libvirt source file, e.g., <code>remote</code>, <code>qemu</code>,
@@ -201,23 +201,23 @@
     </p>
 
     <pre>
- $ journalctl MESSAGE_ID=8ae2f3fb-2dbe-498e-8fbd-012d40afa361 --output=json
- { ...snip...
-   "LIBVIRT_SOURCE" : "file",
-   "PRIORITY" : "3",
-   "CODE_FILE" : "qemu/qemu_capabilities.c",
-   "CODE_LINE" : "2770",
-   "CODE_FUNC" : "virQEMUCapsLogProbeFailure",
-   "MESSAGE_ID" : "8ae2f3fb-2dbe-498e-8fbd-012d40afa361",
-   "LIBVIRT_QEMU_BINARY" : "/bin/qemu-system-xtensa",
-   "MESSAGE" : "Failed to probe capabilities for /bin/qemu-system-xtensa:" \
-               "internal error: Child process (LC_ALL=C LD_LIBRARY_PATH=/home/berrange" \
-               "/src/virt/libvirt/src/.libs PATH=/usr/lib64/ccache:/usr/local/sbin:" \
-               "/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin HOME=/root " \
-               "USER=root LOGNAME=root /bin/qemu-system-xtensa -help) unexpected " \
-               "exit status 127: /bin/qemu-system-xtensa: error while loading shared " \
-               "libraries: libglapi.so.0: cannot open shared object file: No such " \
-               "file or directory\n" }
+$ journalctl MESSAGE_ID=8ae2f3fb-2dbe-498e-8fbd-012d40afa361 --output=json
+{ ...snip...
+  "LIBVIRT_SOURCE" : "file",
+  "PRIORITY" : "3",
+  "CODE_FILE" : "qemu/qemu_capabilities.c",
+  "CODE_LINE" : "2770",
+  "CODE_FUNC" : "virQEMUCapsLogProbeFailure",
+  "MESSAGE_ID" : "8ae2f3fb-2dbe-498e-8fbd-012d40afa361",
+  "LIBVIRT_QEMU_BINARY" : "/bin/qemu-system-xtensa",
+  "MESSAGE" : "Failed to probe capabilities for /bin/qemu-system-xtensa:" \
+              "internal error: Child process (LC_ALL=C LD_LIBRARY_PATH=/home/berrange" \
+              "/src/virt/libvirt/src/.libs PATH=/usr/lib64/ccache:/usr/local/sbin:" \
+              "/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin HOME=/root " \
+              "USER=root LOGNAME=root /bin/qemu-system-xtensa -help) unexpected " \
+              "exit status 127: /bin/qemu-system-xtensa: error while loading shared " \
+              "libraries: libglapi.so.0: cannot open shared object file: No such " \
+              "file or directory\n" }
     </pre>
 
     <h2>