Fix MD025 warnings

The following warnings are generated by using markdownlint analysis:
```
docs/Network-Configuration.md:26 MD025/single-title/single-h1 Multiple top-level headings in the same document [Context: "# DbusObjects"]
docs/Network-Configuration.md:56 MD025/single-title/single-h1 Multiple top-level headings in the same document [Context: "# UseCases"]
```
Refer to markdown-lint [1] to fix MD025
[1]: https://github.com/updownpress/markdown-lint/blob/master/rules/025-single-h1.md

Signed-off-by: George Liu <liuxiwei@ieisystem.com>
Change-Id: I0912159d293b770bf9f5e2b4e398dae344094851
diff --git a/docs/Network-Configuration.md b/docs/Network-Configuration.md
index 7b7004d..fc7b1d9 100644
--- a/docs/Network-Configuration.md
+++ b/docs/Network-Configuration.md
@@ -23,9 +23,9 @@
 5. VLANInterface: This describes the VLAN-specific properties.
 6. Bond: This describes the interface bonding parameters.
 
-# DbusObjects
+## DbusObjects
 
-## Interface Objects
+### Interface Objects
 
 Interface objects can be physical as well as virtual.
 
@@ -34,7 +34,7 @@
 
 Example: `/xyz/openbmc_project/network/eth0`
 
-## IPAddress Objects
+### IPAddress Objects
 
 There can be multiple IP address objects under an interface object. These
 objects can be deleted by the delete function.
@@ -47,15 +47,15 @@
 
 Example: `/xyz/openbmc_project/network/eth0/ipv6/5dfghilp/`
 
-## Conf Object
+### Conf Object
 
 This object will have the system configuration related parameters.
 
 Example: `/xyz/openbmc_project/network/conf`
 
-# UseCases
+## UseCases
 
-## Configure IP address:
+### Configure IP address:
 
 ```sh
 busctl call xyz.openbmc_project.Network /xyz/openbmc_project/network/<interface>
@@ -68,9 +68,9 @@
 }' https://<hostname/ip>/xyz/openbmc_project/network/eth0/action/IP
 ```
 
-## Configure Default Gateway
+### Configure Default Gateway
 
-### Get
+#### Get
 
 ```sh
 busctl get-property xyz.openbmc_project.Network
@@ -81,7 +81,7 @@
 https://<hostname/ip>/xyz/openbmc_project/network/config/attr/DefaultGateway
 ```
 
-### Set
+#### Set
 
 ```sh
 busctl set-property xyz.openbmc_project.Network
@@ -97,9 +97,9 @@
 NOTE: Since the system does not allow unpingable gateway address, make sure the
 gateway address is pingable.
 
-## Configure HostName
+### Configure HostName
 
-### Get
+#### Get
 
 ```sh
 busctl get-property xyz.openbmc_project.Network
@@ -110,7 +110,7 @@
 https://<hostname/ip>/xyz/openbmc_project/network/config/attr/HostName
 ```
 
-### Set
+#### Set
 
 ```sh
 busctl set-property xyz.openbmc_project.Network
@@ -122,7 +122,7 @@
 https://<hostname/ip>/xyz/openbmc_project/network/config/attr/HostName
 ```
 
-## Delete IP address
+### Delete IP address
 
 ```sh
 busctl call xyz.openbmc_project.Network
@@ -138,9 +138,9 @@
 https://<hostname/ip>/xyz/openbmc_project/network/eth0/ipv4/fbfc29b
 ```
 
-## Configure DHCP
+### Configure DHCP
 
-### Get
+#### Get
 
 ```sh
 busctl get-property xyz.openbmc_project.Network
@@ -151,7 +151,7 @@
 https://<hostname/ip>/xyz/openbmc_project/network/eth0/attr/DHCPEnabled
 ```
 
-### Set
+#### Set
 
 ```sh
 busctl set-property xyz.openbmc_project.Network
@@ -162,9 +162,9 @@
 1}' https://<hostname/ip>/xyz/openbmc_project/network/eth0/attr/DHCPEnabled
 ```
 
-## Configure MACAddress
+### Configure MACAddress
 
-### Get
+#### Get
 
 ```sh
 busctl get-property xyz.openbmc_project.Network
@@ -175,7 +175,7 @@
 https://<hostname/ip>/xyz/openbmc_project/network/eth0/attr/MACAddress
 ```
 
-### Set
+#### Set
 
 NOTE: MAC address should be LOCAL ADMIN MAC (2nd bit of first byte should be
 on).
@@ -190,7 +190,7 @@
 https://<hostname/ip>/xyz/openbmc_project/network/eth0/attr/MACAddress
 ```
 
-## Network factory reset
+### Network factory reset
 
 ```sh
 busctl call xyz.openbmc_project.Network /xyz/openbmc_project/network
@@ -200,9 +200,9 @@
 '{"data":[] }' https://<hostname/ip>/xyz/openbmc_project/network/action/Reset
 ```
 
-## VLAN
+### VLAN
 
-### Create
+#### Create
 
 ```sh
 curl -c cjar -b cjar -k -H "Content-Type: application/json" -X POST -d
@@ -210,7 +210,7 @@
 https://<hostname/ip>/xyz/openbmc_project/network/action/VLAN
 ```
 
-### Delete
+#### Delete
 
 ```sh
 curl -c cjar -b cjar -k -H "Content-Type: application/json" -X DELETE
@@ -220,13 +220,13 @@
 xyz.openbmc_project.Object.Delete Delete
 ```
 
-### Enumerate
+#### Enumerate
 
 ```sh
 curl -c cjar -b cjar -k -H "Content-Type: application/json" -X GET
 https://<hostname/ip>/xyz/openbmc_project/network/eth0_50/enumerate
 ```
 
-### Configure IP on VLAN Interface
+#### Configure IP on VLAN Interface
 
 Please refer to the "Configure IP address" section.