correct typos & links in README

Author: McFoggy

README.MD

@@ -6,16 +6,16 @@ This plugin enhances [takezoe/gitbucket](https://github.com/takezoe/gitbucket) b
 
 ### Global Announce
 
-This feature allows to notify gitbucket users. It is available to `admin` via  the `System Administration` menu of gitbucket.
+This feature allows to notify gitbucket users. It is available to _admin_ users via  the `System Administration` menu of gitbucket.
 
 The global announce, sends an email to all active users.
 
-It is then possible, for example, to notify every user that an upgarde of the system is planned the next monday at midday.
+It is then possible, for example, to notify every user that an upgrade of the system is planned the next monday at midday.
 
 ## Usage
 
-- Open a shell window at the root of the project, hit `sbt package` in the root directory of this repository
-- remove any copy of gitbucket-announce-plugin from GITBUCKET_HOME/plugins
+- Open a shell window at the root of the project, hit `sbt package`
+- if you update gitbucket-announce-plugin, remove any existing copy of gitbucket-announce-plugin from GITBUCKET_HOME/plugins
 - Copy target/scala-2.11/gitbucket-announce-plugin_2.11-1.0.jar into GITBUCKET_HOME/plugins
 - Restart GitBucket
 
@@ -25,4 +25,4 @@ It is then possible, for example, to notify every user that an upgarde of the sy
 
 - introduce gitbucket-announce-plugin
 - global announce by email in `System Administration` menu
-- depends on takezoe/gitbucket#861
+- depends on [takezoe/gitbucket#861](https://github.com/takezoe/gitbucket/pull/861)