Update r.rmarkdown.codeLensCommands

Use an enum to restrict the input for the setting: r.rmarkdown.codeLensCommands

Author: ElianHugh

package.json

@@ -1193,13 +1193,25 @@
         "r.rmarkdown.codeLensCommands": {
           "type": "array",
           "items": {
-            "type": "string"
+            "type": "string",
+            "enum": [
+              "r.selectCurrentChunk",
+              "r.runCurrentChunk",
+              "r.runAboveChunks",
+              "r.runCurrentAndBelowChunks",
+              "r.runBelowChunks",
+              "r.runAllChunks",
+              "r.runPreviousChunk",
+              "r.runNextChunk",
+              "r.goToPreviousChunk",
+              "r.goToNextChunk"
+            ]
           },
           "default": [
             "r.runCurrentChunk",
             "r.runAboveChunks"
           ],
-          "description": "Customize RMarkdown CodeLens, which are inline commands/buttons e.g. 'Run Chunk' shown on the first line of each code chunk. Available commands:\n\nr.selectCurrentChunk\nr.runCurrentChunk\nr.runAboveChunks\nr.runCurrentAndBelowChunks\nr.runBelowChunks\nr.runAllChunks\nr.runPreviousChunk\nr.runNextChunk\nr.goToPreviousChunk\nr.goToNextChunk\n\n----------------------------------\nCustomize both the commands AND its orders (that is, CodeLens respect user-specified orders):"
+          "description": "Customize RMarkdown CodeLens, which are inline commands/buttons e.g. 'Run Chunk' shown on the first line of each code chunk. \nCustomize both the commands AND its orders (that is, CodeLens respect user-specified orders):"
         },
         "r.rmarkdown.enableCodeLens": {
           "type": "boolean",