fixtypo:name of default act func is wrong

[DarthThomas]

Motivation

Found a small typo in docstring

Modification

corrected a small typo in docstring

[CLAassistant]

All committers have signed the CLA.

[chhluo]

Thanks.

[codecov]

Codecov Report

Merging #7794 (111b440) into dev (6b87ac2) will increase coverage by 0.66%.
The diff coverage is 81.78%.

@@            Coverage Diff             @@
##              dev    #7794      +/-   ##
==========================================
+ Coverage   63.41%   64.08%   +0.66%     
==========================================
  Files         340      346       +6     
  Lines       27493    28117     +624     
  Branches     4645     4744      +99     
==========================================
+ Hits        17436    18019     +583     
- Misses       9131     9152      +21     
- Partials      926      946      +20     

Flag	Coverage Δ
unittests	64.06% <81.78%> (+0.66%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
mmdet/apis/test.py	12.50% <0.00%> (-0.90%)	⬇️
mmdet/core/bbox/assigners/max_iou_assigner.py	72.36% <ø> (ø)
mmdet/core/post_processing/bbox_nms.py	79.10% <ø> (ø)
mmdet/core/utils/__init__.py	100.00% <ø> (ø)
mmdet/datasets/pipelines/instaboost.py	15.00% <0.00%> (ø)
mmdet/models/backbones/swin.py	81.50% <ø> (ø)
...mdet/models/dense_heads/free_anchor_retina_head.py	16.00% <0.00%> (-0.22%)	⬇️
mmdet/models/dense_heads/ssd_head.py	85.84% <ø> (ø)
mmdet/models/necks/fpn.py	94.66% <ø> (ø)
mmdet/core/utils/dist_utils.py	23.59% <15.38%> (-1.41%)	⬇️
... and 45 more

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[OpenMMLab-Assistant-004]

Hi @DarthThomas ！First of all, we want to express our gratitude for your significant PR in the mmdetection project. Your contribution is highly appreciated, and we are grateful for your efforts in helping improve this open-source project during your personal time. We believe that many developers will benefit from your PR.

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