Update codebox (#9430)

* updated the codeboxes in docs

* codebox change from json to http

docs/sources/plugins/developing/code-styleguide.md

@@ -23,7 +23,7 @@ The most important fields are the first three, especially the id. The convention
 
 Examples:
 
-```
+```bash
 raintank-worldping-app
 grafana-simple-json-datasource
 grafana-piechart-panel
@@ -66,7 +66,7 @@ The README.md file is rendered both on Grafana.net and in the plugins section in
 
 Here is a typical directory structure for a plugin.
 
-```
+```bash
 johnnyb-awesome-datasource
 |-- dist
 |-- spec

docs/sources/plugins/developing/datasources.md

@@ -45,7 +45,7 @@ The javascript object that communicates with the database and transforms data to
 
 The Datasource should contain the following functions:
 
-```
+```javascript
 query(options) //used by panels to get data
 testDatasource() //used by datasource configuration page to make sure the connection is working
 annotationQuery(options) // used by dashboards to get annotations

docs/sources/plugins/installation.md

@@ -30,37 +30,37 @@ On Linux systems the grafana-cli will assume that the grafana plugin directory i
 ### Grafana-cli Commands
 
 List available plugins
-```
+```bash
 grafana-cli plugins list-remote
 ```
 
 Install the latest version of a plugin
-```
+```bash
 grafana-cli plugins install <plugin-id>
 ```
 
 Install a specific version of a plugin
-```
+```bash
 grafana-cli plugins install <plugin-id> <version>
 ```
 
 List installed plugins
-```
+```bash
 grafana-cli plugins ls
 ```
 
 Update all installed plugins
-```
+```bash
 grafana-cli plugins update-all
 ```
 
 Update one plugin
-```
+```bash
 grafana-cli plugins update <plugin-id>
 ```
 
 Remove one plugin
-```
+```bash
 grafana-cli plugins remove <plugin-id>
 ```
 
@@ -73,7 +73,7 @@ The Download URL from Grafana.com API is in this form:
 `https://grafana.com/api/plugins/<plugin id>/versions/<version number>/download`
 
 You can specify a local URL by using the `--pluginUrl` option.
-```
+```bash
 grafana-cli --pluginUrl https://nexus.company.com/grafana/plugins/<plugin-id>-<plugin-version>.zip plugins install <plugin-id>
 ```
 
@@ -84,7 +84,7 @@ To manually install a Plugin via the Grafana.com API:
     {{< imgbox img="/img/docs/installation-tab.png" caption="Installation Tab" >}}
 
 2. Use the Grafana API to find the plugin using this url `https://grafana.com/api/plugins/<plugin id from step 1>`. For example: https://grafana.com/api/plugins/jdbranham-diagram-panel should return:
-    ```
+    ```bash
     {
       "id": 145,
       "typeId": 3,
@@ -97,7 +97,7 @@ To manually install a Plugin via the Grafana.com API:
     ```
 
 3. Find the download link:
-    ```
+    ```bash
     {
        "rel": "download",
        "href": "/plugins/jdbranham-diagram-panel/versions/1.4.0/download"