minor #10903 [Documentation] Fix bad output folder (louvelmathieu)

This PR was submitted for the 4.2 branch but it was merged into the 4.1 branch instead (closes #10903).

Discussion
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[Documentation] Fix bad output folder

Default folder is now "public" and not "web"

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Commits
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e388926 Update installation.rst

Author: javiereguiluz

frontend/encore/installation.rst

@@ -57,7 +57,7 @@ is the main config file for both Webpack and Webpack Encore:
 
     Encore
         // directory where compiled assets will be stored
-        .setOutputPath('web/build/')
+        .setOutputPath('public/build/')
         // public path used by the web server to access the output path
         .setPublicPath('/build')
         // only needed for CDN's or sub-directory deploy