From ec2834463c761dfdccda4da78a3fb382cae14869 Mon Sep 17 00:00:00 2001
From: Junwei Zhao <wahyd4@gmail.com>
Date: Mon, 24 Dec 2018 15:22:17 +1100
Subject: [PATCH] Add some tip for sync.RWMutex

---
 categories/go.md | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/categories/go.md b/categories/go.md
index bcaaa74..c6aa6cc 100644
--- a/categories/go.md
+++ b/categories/go.md
@@ -58,16 +58,24 @@ ch := make(chan Task, 3)
 
 ## Sync
 
-- atomic
-- Mutex
+###  atomic
+### Mutex
     - sync.Mutex()
     - mutex.Lock()
     - mutx.Unlock()
-- string literals
+### RWMutex
+  > A RWMutex is a reader/writer mutual exclusion lock. The lock can be held by an arbitrary number of readers or a single writer. The zero value for a RWMutex is an unlocked mutex.
 
-    \`aaa bbb ccc\`
-- panic / recover
-- `sync.Map` is concurrent/ thread safe `map`, normal `map` isn't
+In other words, readers don't have to wait for each other. They only have to wait for writers holding the lock.
+
+### string literals
+
+```go
+    `aaa bbb ccc`
+```
+### panic / recover
+
+###  `sync.Map` is concurrent/ thread safe `map`, normal `map` isn't
 
 ```go
 m := new(sync.Map)