Documentation/v3: fix broken links

Signed-off-by: Gyu-Ho Lee <gyuhox@gmail.com>

Documentation/dev-internal/logging.md

@@ -3,7 +3,7 @@
 etcd uses the [capnslog][capnslog] library for logging application output categorized into *levels*. A log message's level is determined according to these conventions:
 
 * Error: Data has been lost, a request has failed for a bad reason, or a required resource has been lost
-  * Examples: 
+  * Examples:
     * A failure to allocate disk space for WAL
 
 * Warning: (Hopefully) Temporary conditions that may cause errors, but may work fine. A replica disappearing (that may reconnect) is a warning.
@@ -26,4 +26,4 @@ etcd uses the [capnslog][capnslog] library for logging application output catego
     * Send a normal message to a remote peer
     * Write a log entry to disk
 
-[capnslog]: [https://github.com/coreos/pkg/tree/master/capnslog]
+[capnslog]: https://github.com/coreos/pkg/tree/master/capnslog

Documentation/op-guide/configuration.md

@@ -299,7 +299,7 @@ Follow the instructions when using these flags.
 [build-cluster]: clustering.md#static
 [reconfig]: runtime-configuration.md
 [discovery]: clustering.md#discovery
-[iana-ports]: https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=etcd
+[iana-ports]: http://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.txt
 [proxy]: ../v2/proxy.md
 [restore]: ../v2/admin_guide.md#restoring-a-backup
 [security]: security.md

Documentation/op-guide/grpc_proxy.md

@@ -101,7 +101,7 @@ bar
 
 ## Client endpoint synchronization and name resolution
 
-The proxy supports registering its endpoints for discovery by writing to a user-defined endpoint. This serves two purposes. First, it allows clients to synchronize their endpoints against a set of proxy endpoints for high availability. Second, it is an endpoint provider for etcd [gRPC naming][dev-guide/grpc_naming.md].
+The proxy supports registering its endpoints for discovery by writing to a user-defined endpoint. This serves two purposes. First, it allows clients to synchronize their endpoints against a set of proxy endpoints for high availability. Second, it is an endpoint provider for etcd [gRPC naming](../dev-guide/grpc_naming.md).
 
 Register proxy(s) by providing a user-defined prefix:
 

Documentation/production-users.md

@@ -104,7 +104,7 @@ PD(Placement Driver) is the central controller in the TiDB cluster. It saves the
 
 ## QingCloud
 
-- *Application*: [QingCloud](qingcloud) appcenter cluster for service discovery as [metad](metad) backend.
+- *Application*: [QingCloud][qingcloud] appcenter cluster for service discovery as [metad][metad] backend.
 - *Launched*: December 2016
 - *Cluster Size*: 1 cluster of 3 members per user.
 - *Order of Data Size*: kilobytes
@@ -186,7 +186,7 @@ In [hyper.sh][hyper.sh], the container service is backed by [hypernetes][hyperne
 - *Cluster Size*: 1000+ deployments, each deployment contains a 3 node cluster.
 - *Order of Data Size*: 100s of Megabytes
 - *Operator*: daocloud.io
-- *Environment*: Baremetal and virtual machines 
+- *Environment*: Baremetal and virtual machines
 - *Backups*: None, all data can be recreated if necessary.
 
 In [DaoCloud][DaoCloud], we use Docker and Swarm to deploy and run our applications, and we use etcd to save metadata for service discovery.
@@ -203,8 +203,9 @@ In [DaoCloud][DaoCloud], we use Docker and Swarm to deploy and run our applicati
 - *Environment*: AWS, Kubernetes
 - *Backups*: EBS volume backups
 
-At Branch, we use kubernetes heavily as our core microservice platform for staging and production. 
-[Branch]:https://branch.io
+At [Branch][branch], we use kubernetes heavily as our core microservice platform for staging and production.
+
+[branch]: https://branch.io
 
 ## Baidu Waimai
 
@@ -213,7 +214,7 @@ At Branch, we use kubernetes heavily as our core microservice platform for stagi
 - *Cluster Size*: 3 clusters of 5 members
 - *Order of Data Size*: several gigabytes
 - *Operator*: Baidu Waimai Operations Department
-- *Environment*: CentOS 6.5 
+- *Environment*: CentOS 6.5
 - *Backups*: backup scripts
 
 ## Salesforce.com

Documentation/reporting_bugs.md

@@ -1,6 +1,6 @@
 # Reporting bugs
 
-If any part of the etcd project has bugs or documentation mistakes, please let us know by [opening an issue][issue]. We treat bugs and mistakes very seriously and believe no issue is too small. Before creating a bug report, please check that an issue reporting the same problem does not already exist.
+If any part of the etcd project has bugs or documentation mistakes, please let us know by [opening an issue][etcd-issue]. We treat bugs and mistakes very seriously and believe no issue is too small. Before creating a bug report, please check that an issue reporting the same problem does not already exist.
 
 To make the bug report accurate and easy to understand, please try to create bug reports that are: