feat(plugin): support label property for Bug Report button (#11)

* #3 add label option

* #3 add label usage on README

* #3 remove unnecessary property for explanation

Author: ryo-gk

README.md

@@ -53,6 +53,26 @@ For private repositories, set this flag.
 }
 ```
 
+- `label`: button label (optional, default is `Bug Report`)
+
+Set button label if you want to use other than default.
+
+```json
+{
+    "gitbook": ">=3.0.0",
+    "title": "Example",
+    "plugins": [
+        "github-issue-feedback"
+    ],
+    "pluginsConfig": {
+        "github-issue-feedback": {
+            "repo": "your/private_repo",
+            "label": "Report Issue on GitHub"
+        }
+    }
+}
+```
+
 ## Changelog
 
 See [Releases page](https://github.com/azu/gitbook-plugin-github-issue-feedback/releases).

src/plugin.js

@@ -62,7 +62,7 @@ window.require(["gitbook"], function(gitbook) {
     gitbook.events.bind("start", function(e, pluginConfig) {
         var config = pluginConfig["github-issue-feedback"];
         var reportElement = document.createElement("button");
-        reportElement.textContent = "Bug Report";
+        reportElement.textContent = config["label"] || "Bug Report";
         reportElement.className = "gitbook-plugin-github-issue-feedback";
         reportElement.setAttribute("style", "position:fixed; right:0;bottom:0;");
         var clickEvent = ("ontouchstart" in window) ? "touchend" : "click";