MISC: update README and migration comment

README.md

@@ -1,4 +1,4 @@
-Gogs [![Build Status](https://travis-ci.org/gogits/gogs.svg?branch=master)](https://travis-ci.org/gogits/gogs) [![Build status](https://ci.appveyor.com/api/projects/status/b9uu5ejl933e2wlt/branch/master?svg=true)](https://ci.appveyor.com/project/Unknwon/gogs/branch/master) [![Crowdin](https://d322cqt584bo4o.cloudfront.net/gogs/localized.svg)](https://crowdin.com/project/gogs) [![Sourcegraph](https://sourcegraph.com/github.com/gogits/gogs/-/badge.svg)](https://sourcegraph.com/github.com/gogits/gogs?badge) [![Gitter](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/gogits/gogs?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+Gogs [![Build Status](https://travis-ci.org/gogits/gogs.svg?branch=master)](https://travis-ci.org/gogits/gogs) [![Build status](https://ci.appveyor.com/api/projects/status/b9uu5ejl933e2wlt/branch/master?svg=true)](https://ci.appveyor.com/project/Unknwon/gogs/branch/master) [![Crowdin](https://d322cqt584bo4o.cloudfront.net/gogs/localized.svg)](https://crowdin.com/project/gogs)
 =====================
 
 ![](https://github.com/gogits/gogs/blob/master/public/img/gogs-large-resize.png?raw=true)

models/migrations/v15.go

@@ -67,6 +67,8 @@ func generateAndMigrateGitHooks(x *xorm.Engine) (err error) {
 			wikiPath := repoBase + ".wiki.git"
 			log.Trace("[%04d]: %s", idx, repoPath)
 
+			// Note: we should not create hookDir here because update hook file should already exists inside this direcotry,
+			// if this directory does not exist, the current setup is not correct anyway.
 			hookDir := filepath.Join(repoPath, "hooks")
 			customHookDir := filepath.Join(repoPath, "custom_hooks")
 			wikiHookDir := filepath.Join(wikiPath, "hooks")