docs: Remove colon from ctltable title in vm.rst

Removing them solves an issue where they were incorrectly considered as
not implemented by the check-sysctl-docs script

Signed-off-by: Joel Granados <joel.granados@kernel.org>

Author: Joelgranados

Documentation/admin-guide/sysctl/vm.rst

@@ -465,8 +465,8 @@ The minimum value is 1 (1/1 -> 100%). The value less than 1 completely
 disables protection of the pages.
 
 
-max_map_count:
-==============
+max_map_count
+=============
 
 This file contains the maximum number of memory map areas a process
 may have. Memory map areas are used as a side-effect of calling
@@ -495,8 +495,8 @@ memory allocations.
 The default value depends on CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT.
 
 
-memory_failure_early_kill:
-==========================
+memory_failure_early_kill
+=========================
 
 Control how to kill processes when uncorrected memory error (typically
 a 2bit error in a memory module) is detected in the background by hardware