Add indexer doc about AeFinder introduction and how to set up an AeFinder plugin

[xiboXD]

No description provided.

[vizipi]

Pull request analysis by VIZIPI

Below you will find who is the most qualified team member to review your code.
This analysis includes his/her work on the code included in this Pull request, in addition to their experience in code affected by these changes ( partly found within the list of potential missing files below )   Feedback always welcome

Reviewers with knowledge related to these changes

Match %	Person	Commit Count	Common Files
100.00%	xibo	7	4
25.00%	AbigailDeng	9	1
25.00%	ZhangXin	7	1
25.00%	wangyue	5	1
25.00%	eanzhao	5	1
25.00%	lhoopox	2	1

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Potential missing files from this Pull request

No commonly committed files found with a 40% threashold

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Committed file ranks

(click to expand)

50.55%[docs-sphinx/tutorials/indexer/index.rst]

93.40%[docs-sphinx/index.rst]

57.21%[...docs-sphinx/tutorials/indexer/build-an-aelf-indexer-plugi]

40.40%[docs-sphinx/tutorials/indexer/aelf-indexer-introduction.rst]

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (107aacf) 91.05% compared to head (96a69e5) 91.05%.
Report is 6 commits behind head on docs.

Additional details and impacted files

@@           Coverage Diff           @@
##             docs    #3520   +/-   ##
=======================================
  Coverage   91.05%   91.05%           
=======================================
  Files         619      619           
  Lines       23682    23682           
  Branches     2093     2093           
=======================================
  Hits        21563    21563           
  Misses       1988     1988           
  Partials      131      131