lmkd: Update documentation of a couple defaults

We updated a couple of these default values in the code in previous CLs:
- https://android-review.googlesource.com/c/platform/system/memory/lmkd/+/1358623
- https://android-review.googlesource.com/c/platform/system/memory/lmkd/+/1314688

We now update the README.md to reflect those code changes.

Bug: 405461921
Test: N/A
Change-Id: If802c1cbd9bcc0a88fc7870213b98ef062676d58

README.md

@@ -60,14 +60,13 @@ properties:
                                  any eligible task (fast decision). Default = false
 
   - `ro.lmk.kill_timeout_ms`:    duration in ms after a kill when no additional
-                                 kill will be done. Default = 0 (disabled)
+                                 kill will be done. Default = 100
 
   - `ro.lmk.debug`:              enable lmkd debug logs, Default = false
 
   - `ro.lmk.swap_free_low_percentage`: level of free swap as a percentage of the
                                  total swap space used as a threshold to consider
-                                 the system as swap space starved. Default for
-                                 low-RAM devices = 10, for high-end devices = 20
+                                 the system as swap space starved. Default = 10
 
   - `ro.lmk.thrashing_limit`:    number of workingset refaults as a percentage of
                                 the file-backed pagecache size used as a threshold