Fix typos in docs/extend developer documentation (#50009)

* Initial plan

* Fix typos in docs/extend developer documentation

- vizualizations → visualizations in export-dashboards.md
- perfomed running → performed by running in testing.md
- writen → written in filebeat-modules-devguide.md
- custome → custom in event-fields-yml.md

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Co-authored-by: strawgate <6384545+strawgate@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: strawgate <6384545+strawgate@users.noreply.github.com>
Co-authored-by: Bill Easton <bill.easton@elastic.co>
Co-authored-by: Visha Angelova <91186315+vishaangelova@users.noreply.github.com>

Author: 3 people

docs/extend/event-fields-yml.md

@@ -162,7 +162,7 @@ For example, you can define a new text analyzer that does not break hyphenated n
 ```
 
 1. Use a newly defined text analyzer
-2. Define the custome analyzer type
+2. Define the custom analyzer type
 3. Specify the analyzer behaviour
 4. Use the same analyzer for the search
 

docs/extend/export-dashboards.md

@@ -39,7 +39,7 @@ MODULE=redis ID=AV4REOpp5NkDleZmzKkE mage exportDashboard
 ./filebeat export dashboard --id 7fea2930-478e-11e7-b1f0-cb29bac6bf8b --folder module/redis
 ```
 
-This generates an appropriate folder under module/redis for the dashboard, separating assets into dashboards, searches, vizualizations, etc. Each exported file is a JSON and their names are the IDs of the assets.
+This generates an appropriate folder under module/redis for the dashboard, separating assets into dashboards, searches, visualizations, etc. Each exported file is a JSON and their names are the IDs of the assets.
 
 ::::{note}
 The dashboard ID is available in the dashboard URL. For example, in case the dashboard URL is `app/kibana#/dashboard/AV4REOpp5NkDleZmzKkE?_g=()&_a=(description:'Overview%2...`, the dashboard ID is `AV4REOpp5NkDleZmzKkE`.

docs/extend/filebeat-modules-devguide.md

@@ -428,7 +428,7 @@ In order to test the filesets with the sample logs and/or generate the expected
     * `GENERATE`: if set to 1, the expected documents will be generated.
 
 
-The filebeat logs are writen to the `build` directory. It may be useful to tail them in another terminal using `tail -F build/system-tests/run/test_modules.Test.*/output.log`.
+The filebeat logs are written to the `build` directory. It may be useful to tail them in another terminal using `tail -F build/system-tests/run/test_modules.Test.*/output.log`.
 
 For example if there’s a syntax error in an ingest pipeline, the test will probably just hang. The filebeat log output will contain the error message from elasticsearch.
 

docs/extend/testing.md

@@ -57,7 +57,7 @@ mage docker:composeDown
 
 Go tests support generating sample events to be used as fixtures.
 
-This generation can be perfomed running `go test --data`. This functionality is supported by packetbeat and Metricbeat.
+This generation can be performed by running `go test --data`. This functionality is supported by packetbeat and Metricbeat.
 
 In Metricbeat, run the command from within a module like this: `go test --tags integration,azure --data --run "TestData"`. Make sure to add the relevant tags (`integration` is common then add module and metricset specific tags).