[ES|QL] Removes SHOW functions from docs (elastic#220652)

## Summary

Removes `Show functions` from our docs as it is not supported anymore

<img width="487" alt="image"
src="https://github.com/user-attachments/assets/ca385cb4-d96f-4730-891f-b9b50bd34a35"
/>

Author: stratoula

src/platform/packages/private/kbn-language-documentation/src/sections/esql_documentation_sections.tsx

@@ -145,10 +145,7 @@ ROW a = ROUND(1.23, 0)
         <Markdown
           markdownContent={i18n.translate('languageDocumentation.documentationESQL.show.markdown', {
             defaultMessage: `### SHOW
-The \`SHOW <item>\` source command returns information about the deployment and its capabilities:
-
-* Use \`SHOW INFO\` to return the deployment's version, build date and hash.
-* Use \`SHOW FUNCTIONS\` to return a list of all supported functions and a synopsis of each function.
+The \`SHOW INFO\` source command returns the deployment's version, build date and hash.
             `,
             ignoreTag: true,
             description: