docs: remove the reference of the old agent skills

quickstart.sh

@@ -1204,14 +1204,6 @@ else
     echo -e "${YELLOW}--${NC}"
 fi
 
-echo -n "  ⬡ skills... "
-if [ -d "$SCRIPT_DIR/.claude/skills" ]; then
-    SKILL_COUNT=$(ls -1d "$SCRIPT_DIR/.claude/skills"/*/ 2>/dev/null | wc -l)
-    echo -e "${GREEN}${SKILL_COUNT} found${NC}"
-else
-    echo -e "${YELLOW}--${NC}"
-fi
-
 echo -n "  ⬡ codex CLI... "
 if command -v codex > /dev/null 2>&1; then
     CODEX_VERSION=$(codex --version 2>/dev/null | head -1 | grep -oE '[0-9]+\.[0-9]+\.[0-9]+' || echo "0.0.0")