[CI/i18n/pt] Illustrate notes for pt and drop _param shortcode

[chalin]

• Contributes to Improved i18n support #4467
• In support of [pt] Localize content/pt/docs/languages/js/getting-started/ #6071
• Drops the site-local _param shortcode in favor of the Hugo param, which might not have worked with markdown, but it does now
• Adds param notes.browser-instrumentation under the languages.pt.params as an illustration of how such notes should be defined for non-en locales

There is no change to the generated site files other than the updated pt note, which is now in Portuges instead of English:

$ (cd public && git diff -bw --ignore-blank-lines -- . ':(exclude)*.xml') | grep ^diff
diff --git a/pt/docs/languages/js/getting-started/browser/index.html b/pt/docs/languages/js/getting-started/browser/index.html
diff --git a/pt/docs/languages/js/index.html b/pt/docs/languages/js/index.html
diff --git a/pt/docs/languages/js/instrumentation/index.html b/pt/docs/languages/js/instrumentation/index.html
diff --git a/site/index.html b/site/index.html