[DOC] Replace Firestorm with Uniffle

[jerqi]

What changes were proposed in this pull request?

Replace Firestorm with Uniffle in the document

Why are the changes needed?

Project was renamed to Uniffle

Does this PR introduce any user-facing change?

No

How was this patch tested?

No need

[codecov-commenter]

Codecov Report

Merging #60 (5e8ebff) into master (cbe39c1) will decrease coverage by 1.69%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master      #60      +/-   ##
============================================
- Coverage     56.86%   55.17%   -1.70%     
+ Complexity     1208     1111      -97     
============================================
  Files           152      148       -4     
  Lines          8437     7962     -475     
  Branches        819      760      -59     
============================================
- Hits           4798     4393     -405     
+ Misses         3378     3328      -50     
+ Partials        261      241      -20     

Impacted Files	Coverage Δ
...iffle/storage/handler/impl/ShuffleIndexHeader.java	0.00% <0.00%> (-77.56%)	⬇️
...a/org/apache/uniffle/server/RegisterHeartBeat.java	42.59% <0.00%> (-44.45%)	⬇️
...e/uniffle/storage/handler/impl/HdfsFileWriter.java	55.22% <0.00%> (-28.36%)	⬇️
...storage/handler/impl/DataSkippableReadHandler.java	84.37% <0.00%> (-9.38%)	⬇️
.../java/org/apache/uniffle/server/ShuffleServer.java	64.70% <0.00%> (-7.57%)	⬇️
...ache/uniffle/storage/util/ShuffleStorageUtils.java	61.00% <0.00%> (-6.33%)	⬇️
.../java/org/apache/hadoop/mapreduce/RssMRConfig.java	87.50% <0.00%> (-4.17%)	⬇️
.../java/org/apache/uniffle/common/BufferSegment.java	96.15% <0.00%> (-3.85%)	⬇️
...org/apache/uniffle/common/config/ConfigOption.java	60.86% <0.00%> (-2.77%)	⬇️
...niffle/storage/common/FileBasedShuffleSegment.java	51.51% <0.00%> (-1.43%)	⬇️
... and 30 more

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