Remove backslashed newlines on markdown (go-gitea#26344)

Fix https://gitea.com/gitea/gitea-docusaurus/issues/56

Author: lunny

docs/content/usage/agit-support.en-us.md

@@ -21,8 +21,8 @@ In Gitea `1.13`, support for [agit](https://git-repo.info/en/2020/03/agit-flow-a
 
 ## Creating PRs with Agit
 
-Agit allows to create PRs while pushing code to the remote repo. \
-This can be done by pushing to the branch followed by a specific refspec (a location identifier known to git). \
+Agit allows to create PRs while pushing code to the remote repo.
+This can be done by pushing to the branch followed by a specific refspec (a location identifier known to git).
 The following example illustrates this:
 
 ```shell