Add Migration Guide for v0.12.0 (#343)

Add Migration Guide: v0.11 to v0.12

Co-authored-by: 6543 <6543@obermui.de>
Reviewed-on: https://gitea.com/gitea/go-sdk/pulls/343
Reviewed-by: Andrew Thornton <art27@cantab.net>
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>

docs/migrate-v0.11-to-v0.12.md

@@ -0,0 +1,120 @@
+# Migration Guide: v0.11 to v0.12
+
+v0.12.0 introduces a number of breaking changes, throu it should not be hard to
+migrate.
+Just follow this guid and if issues still ocure ask for help on discord or
+feel free to create an issue.
+
+<!-- toc -->
+
+-   [List Functions now always need an ListOption as argument (#205) (#243) (244)](#List-Functions-now-always-need-an-ListOption-as-argument)
+-   [Authentification was removed from all Functions (#241) (#335)](Authentification-was-removed-from-all-Functions)
+-   [Some Functions where deleted (#247) (#262)](Some-Functions-where-deleted)
+-   [SearchUsers arguments are move to an Option struct (#248)](SearchUsers-arguments-are-move-to-an-Option-struct)
+-   [RepoTopics functions now expect and return string slice directly (#276)](ListRepoTopics-return-now-string-slice-directly)
+-   [MergePullRequestOption field names changed and Enum is now used (#328)](MergePullRequestOption-field-names-changed-and-Enum-is-now-used)
+
+<!-- tocstop -->
+
+## List Functions now always need an ListOption as argument
+
+since paggination is introduced in gitea v1.12.0 for all list endpoints,
+all List Functions acept at least **Page** and **PageSize**.
+
+If the function had had already an Option struct as argument this one is now extendet,
+if not a new Options type was created.
+
+-   migrate old paggination arguments to the new One.
+-   add a empty Option struct if a new one was created.
+
+Pulls:
+
+-   [#205 Add Pagination Options for List Requests](https://gitea.com/gitea/go-sdk/pulls/205)
+-   [#243 Add ListIssueCommentOptions for optional param](https://gitea.com/gitea/go-sdk/pulls/243)
+-   [#244 Add ListMilestoneOption to ListRepoMilestones](https://gitea.com/gitea/go-sdk/pulls/244)
+
+## Authentification was removed from all Functions
+
+for Authentification the default credentials/token is used,
+witch was set on Client initialisation.
+
+for RepoWatch functions remove arguments:
+
+-   GetWatchedRepos: password (second)
+-   WatchRepo: username (first), password (second)
+-   UnWatchRepo: username (first), password (second)
+
+for Token functions remove:
+
+-   the first two argument (user & password),
+    these functions still relay on BasicAuth so if not done,
+    just set username, password and optional otp before executing them.
+
+```go
+client.SetBasicAuth(username, password)
+client.SetOTP(otp)
+```
+
+Pulls:
+
+-   [#241 Refactor RepoWatch](https://gitea.com/gitea/go-sdk/pulls/241)
+-   [#335 Support 2FA for basic auth & Refactor Token functions](https://gitea.com/gitea/go-sdk/pulls/335)
+
+## Some Functions where deleted
+
+Functions where deleted because they where only workarounds
+or are helper functions witch could be replaced easely.
+
+-   BasicAuthEncode
+    if you realy need this just copy the function into your project:
+    ```go
+    func BasicAuthEncode(user, pass string) string {
+    		  return base64.StdEncoding.EncodeToString([]byte(user + ":" + pass))
+    }
+    ```
+-   ListUserIssues
+    If you realy need this just use the Workaround witch was removed with #262
+    and If you have time a pull upstream to gitea for a real API is always wellcome
+
+Pulls:
+
+-   [#247 Fix & Refactor UserApp Functions](https://gitea.com/gitea/go-sdk/pulls/247)
+-   [#262 Remove ListUserIssues](https://gitea.com/gitea/go-sdk/pulls/262)
+
+## SearchUsers arguments are move to an Option struct
+
+Old:
+ `client.SearchUsers(query, limit)`
+New:
+ `client.SearchUsers(SearchUsersOption{KeyWord: "query", Page: 1, PageSize: limit})`
+
+Pull: [#248 extend SearchUsers](https://gitea.com/gitea/go-sdk/pulls/248)
+
+## ListRepoTopics return now string slice directly
+
+ListRepoTopics returned a struct with Topics string slice.
+Now it return the falue of this string slice directly
+
+Old:
+
+```go
+client.SetRepoTopics(user, repo, TopicsList{topic_slice})
+```
+
+New:
+
+```go
+client.SetRepoTopics(user, repo, topic_slice)
+```
+
+Pull: [#276 Refactor List/SetRepoTopics](https://gitea.com/gitea/go-sdk/pulls/276)
+
+## MergePullRequestOption field names changed and Enum is now used
+
+Rename **MergeTitleField** to **Title**
+Rename **MergeMessageField** to **Message**
+
+Do is now called Style and expect predefined falues:
+MergeStyleMerge, MergeStyleRebase, MergeStyleRebaseMerge & MergeStyleSquash
+
+Pull: [#328 PullMerge: use enum for MergeStyle](https://gitea.com/gitea/go-sdk/pulls/328)