[MINOR][DOC] Correct configuration values ​​in slotsallocation

### What changes were proposed in this pull request?

### Why are the changes needed?
Config `celeborn.master.slot.assign.loadAware.fetchTimeWeight` default value is 1, and slotsallocation document is configured as 0.

### Does this PR introduce _any_ user-facing change?
No

### How was this patch tested?
GA

Closes #3287 from cxzl25/minor_doc_slot.

Authored-by: sychen <[email protected]>
Signed-off-by: Wang, Fei <[email protected]>
(cherry picked from commit 14d7212)
Signed-off-by: Wang, Fei <[email protected]>

Author: cxzl25

docs/developers/slotsallocation.md

@@ -32,7 +32,7 @@ celeborn.master.slot.assign.policy LOADAWARE
 celeborn.master.slot.assign.loadAware.numDiskGroups 5
 celeborn.master.slot.assign.loadAware.diskGroupGradient 0.1
 celeborn.master.slot.assign.loadAware.flushTimeWeight 0
-celeborn.master.slot.assign.loadAware.fetchTimeWeight 0
+celeborn.master.slot.assign.loadAware.fetchTimeWeight 1
 [spark.client.]celeborn.storage.availableTypes HDD,SSD
 ```
 ### Detail
@@ -73,4 +73,4 @@ If a worker has multiple disks, the chosen disk index is `(monotone increasing d
 ## Celeborn Worker's Behavior
 1. When reserve slots Celeborn worker will decide a slot be placed in local disks or HDFS when reserve slots.
 2. If a partition is evicted from memory, the partition might be placed in HDFS.
-3. If a slot is explicitly assigned to HDFS, worker will put the slot in HDFS. 
+3. If a slot is explicitly assigned to HDFS, worker will put the slot in HDFS.