docs: admin-guide/sysctl: Fix rendering error

Text in ``literal`` markup must be separated by word separators, so text
like ``lowwater``% renders incorrectly.  Add the suggested "\ " after two
problematic occurrences.
Signed-off-by: Stephen Kitt <steve@sk2.org>
Link: https://lore.kernel.org/r/20220624110230.595740-1-steve@sk2.org
[jc: tweaked to use "\ "]
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/admin-guide/sysctl/kernel.rst

@@ -38,8 +38,8 @@ acct
 
 If BSD-style process accounting is enabled these values control
 its behaviour. If free space on filesystem where the log lives
-goes below ``lowwater``% accounting suspends. If free space gets
-above ``highwater``% accounting resumes. ``frequency`` determines
+goes below ``lowwater``\ % accounting suspends. If free space gets
+above ``highwater``\ % accounting resumes. ``frequency`` determines
 how often do we check the amount of free space (value is in
 seconds). Default: