chore: add new keywords to package json (#6813)

This change adds "feature flag" and "flag" to the keywords in the
package.json file. We've started moving towards using that over feature
toggle, so it makes sense to add it to the keywords.

package.json

@@ -2,7 +2,14 @@
   "name": "unleash-server",
   "description": "Unleash is an enterprise ready feature toggles service. It provides different strategies for handling feature toggles.",
   "version": "5.11.0+main",
-  "keywords": ["unleash", "feature toggle", "feature", "toggle"],
+  "keywords": [
+    "unleash",
+    "feature toggle",
+    "feature",
+    "toggle",
+    "feature flag",
+    "flag"
+  ],
   "files": [
     "dist",
     "docs",