Increase vm map limit recommendation (#14892)

Give some more buffer from 400k

docs/src/running-validator/validator-start.md

@@ -83,7 +83,7 @@ sudo sysctl -p /etc/sysctl.d/20-solana-udp-buffers.conf
 ```bash
 sudo bash -c "cat >/etc/sysctl.d/20-solana-mmaps.conf <<EOF
 # Increase memory mapped files limit
-vm.max_map_count = 500000
+vm.max_map_count = 700000
 EOF"
 ```
 ```bash

sys-tuner/src/main.rs

@@ -93,7 +93,7 @@ fn tune_kernel_udp_buffers_and_vmmap() {
     sysctl_write("net.core.wmem_default", "134217728");
 
     // increase mmap counts for many append_vecs
-    sysctl_write("vm.max_map_count", "500000");
+    sysctl_write("vm.max_map_count", "700000");
 }
 
 #[cfg(unix)]