Add example of using static_key_enabled to patch-author-guild.md

doc/patch-author-guide.md

@@ -808,6 +808,41 @@ This can be done by replacing any usages of `static_branch_likely()`,
 `static_branch_unlikely()`, `static_key_true()`, and `static_key_false()` with
 `static_key_enabled()` in the patch file.
 
+There is an example  of using `static_key_enabled()` to replace the static key in the patch file:
+This is an static key used in the patch file:
+```
+static inline bool memcg_kmem_enabled(void)
+{
+    return static_branch_unlikely(&memcg_kmem_enabled_key);
+}
+``` 
+
+We can use `static_key_enabled()` to rewrite the macros `static_branch_likely` as follows:
+```
+#define static_branch_unlikely(x) unlikely(static_key_enabled(&(x)->key))
+```
+
+However, using the following method to fix the static key error also work:
+```
+static inline bool memcg_kmem_enabled(void)
+{
+    return unlikely(&(&memcg_kmem_enabled_key)->key);
+}
+```
+
+Changing the definition in header file may cause too much changes in the object invoked this macros eventhough we have no changes effect them,
+ which is not a good choice to rewrite the original definition. 
+So, we can define a new function for our patch function to fix static_key.
+```
+static inline bool memcg_kmem_enabled_new(void)
+{
+	return unlikely(&(&memcg_kmem_enabled_key)->key);
+}
+```
+The patch function invoke `memcg_kmem_enabled_new` can avoid changes to other extraneous functions.
+
+
+
 ### Static calls
 
 Similarly, static calls are not supported when the corresponding static call