Updates user guide docs to show text searching example

[teresam856]

Adds section under user guide, and updates statement to reflect name searching is now available in JBrowse2

[teresam856]

We can use this PR to address feedback regarding text searching docs.

[codecov]

Codecov Report

Merging #2290 (23a6ebf) into main (30c5d73) will not change coverage.
The diff coverage is n/a.

❗ Current head 23a6ebf differs from pull request most recent head aa2f10b. Consider uploading reports for the commit aa2f10b to get more accurate results

@@           Coverage Diff           @@
##             main    #2290   +/-   ##
=======================================
  Coverage   62.87%   62.87%           
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  Files         502      502           
  Lines       23213    23213           
  Branches     5313     5313           
=======================================
  Hits        14595    14595           
  Misses       8346     8346           
  Partials      272      272           

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