[i18n] Convert keep-up-to-date.md to an include

[chalin]

• Contributes to Improved i18n support #4467
• Fixes [i18n] Rework shortcodes/ecosystem/keep-up-to-date.md for better localization support #6381
• Extends the functionality of include to support positional and named arguments
• Similar to [i18n] Make instrumentation-intro shortcode a simple include #6364, this converts the keep-up-to-date.md into an include file but this time with an argument
• Renames include.md to include.html so that we could use the . RenderShortcodes functionality, which is required if we want the included file content to be accessible for processing by the markdown renderer (e.g., which allows for headings from the included content to show up in the ToC).

Previews:

• https://deploy-preview-6383--opentelemetry.netlify.app/ecosystem/adopters/#keeping-adopter-information-current
• https://deploy-preview-6383--opentelemetry.netlify.app/ecosystem/vendors/#keeping-vendor-information-current
• https://deploy-preview-6383--opentelemetry.netlify.app/docs/languages/js/getting-started/browser/ showing that the alert (at the top of the page) still renders properly.

The only files with meaningful changes are those that include content/en/docs/languages/js/_browser-instrumentation-warning.md (the pages under /js/) and this is because of our switch from alert-md to the alert shortcode:

$ (cd public && git diff -bw --ignore-blank-lines -I "’|'" -I 'modified_time|dateModified|Last modified') | grep ^diff | grep -Ev '/(es|fr|ja|pt|zh)/' | grep -v sitemap
diff --git a/docs/languages/js/getting-started/browser/index.html b/docs/languages/js/getting-started/browser/index.html
diff --git a/docs/languages/js/index.html b/docs/languages/js/index.html
diff --git a/docs/languages/js/instrumentation/index.html b/docs/languages/js/instrumentation/index.html
diff --git a/site/index.html b/site/index.html

[chalin]

@open-telemetry/docs-pt-approvers @vitorvasc - I'll let you update the included word (here and in the other pt pages) name when you localize keep-up-to-date.md.

[tiffany76]

RSLGTM.