Update map.sh

[rmdhfz]

This pull request optimizes and fixes the bash script by making the following changes:

• Replaced #!/bin/sh with #!/bin/bash to ensure that the script uses bash instead of sh.
• Renamed the findURL function to find_url to conform to the standard naming convention in bash.
• Used double quotes instead of single quotes in the find_url function to allow variable expansion.
• Used sed instead of cut to extract the lesson name from the article filename in the find_url function.
• Used cd instead of pushd and popd to change directories.
• Used while read -r instead of echo "$mapping" | while read to avoid a subshell and potential issues with whitespace in the input.
• Replaced sed "s/[0-9]* //" with cut -d' ' -f2- to extract the title from the mapping input.

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