adding replays for client-side note for both setup docs

Author: Shannon Anahata

docs/platforms/javascript/guides/nextjs/index.mdx

@@ -69,6 +69,7 @@ Sentry.init({
     Sentry.browserTracingIntegration(),
     // ___PRODUCT_OPTION_END___ performance
     // ___PRODUCT_OPTION_START___ session-replay
+    // Replay may only be enabled for the client-side
     Sentry.replayIntegration(),
     // ___PRODUCT_OPTION_END___ session-replay
     // ___PRODUCT_OPTION_START___ user-feedback
@@ -93,8 +94,7 @@ Sentry.init({
   tracesSampleRate: 1.0,
   // ___PRODUCT_OPTION_END___ performance
   // ___PRODUCT_OPTION_START___ session-replay
-
-  // Capture Replay for 10% of all sessions,
+  // Capture Replay for 10% of all 
   // plus for 100% of sessions with an error
   // Learn more at
   // https://docs.sentry.io/platforms/javascript/session-replay/configuration/#general-integration-configuration

docs/platforms/javascript/guides/nextjs/manual-setup.mdx

@@ -129,6 +129,7 @@ Sentry.init({
   // ___PRODUCT_OPTION_END___ performance
   integrations: [
     // ___PRODUCT_OPTION_START___ session-replay
+    // Replay may only be enabled for the client-side
     Sentry.replayIntegration(),
     // ___PRODUCT_OPTION_END___ session-replay
     // ___PRODUCT_OPTION_START___ user-feedback