Fix MD034 warnings

The following warnings are generated by using markdownlint analysis:
```
docs/configuration.md:12:15 MD034/no-bare-urls Bare URL used [Context: "https://github.com/openbmc/ope..."]
```
Refer to markdown-lint [1] to fix MD034
[1]: https://github.com/updownpress/markdown-lint/blob/master/rules/034-no-bare-urls.md

Signed-off-by: George Liu <liuxiwei@ieisystem.com>
Change-Id: I7a59e3789cd549beca1e167c53ddacd97e96c86e
diff --git a/docs/configuration.md b/docs/configuration.md
index 67e588f..139f025 100644
--- a/docs/configuration.md
+++ b/docs/configuration.md
@@ -9,9 +9,7 @@
 phosphor-ipmi-host.bbappend with an ODM or platform customizable configuration.
 
 For a specific example, see:
-[Witherspoon](https://github.com/openbmc/openbmc/blob/master/
-meta-openbmc-machines/meta-openpower/meta-ibm/meta-witherspoon/
-recipes-phosphor/ipmi/phosphor-ipmi-host.bbappend)
+[Witherspoon](https://github.com/openbmc/openbmc/blob/master/meta-openbmc-machines/meta-openpower/meta-ibm/meta-witherspoon/recipes-phosphor/ipmi/phosphor-ipmi-host.bbappend)
 
 The JSON format for get_device_id: