Update comments for appendBlockFromStream and appendBlockFromText, unblock the API usage in parallel

lib/services/blob/blobservice.core.js

@@ -4024,8 +4024,10 @@ BlobService.prototype.appendFromText = function (container, blob, text, optionsO
 
 /**
 * Creates a new block from a read stream to be appended to an append blob.
-* This API should be used strictly in a single writer scenario because the API internally uses the append-offset conditional header to avoid duplicate blocks.
+* If the sequence of data to be appended is important, please use this API strictly in a single writer.
 * If you are guaranteed to have a single writer scenario, please look at options.absorbConditionalErrorsOnRetry and see if setting this flag to true is acceptable for you.
+* If the sequence of data to be appended is not important, this API can be used in parallel,
+* in this case, options.appendPosition can be left without settings.
 *
 * @this {BlobService}
 * @param {string}             container                                 The container name.
@@ -4078,8 +4080,10 @@ BlobService.prototype.appendBlockFromStream = function (container, blob, readStr
 
 /**
 * Creates a new block from a text to be appended to an append blob.
-* This API should be used strictly in a single writer scenario because the API internally uses the append-offset conditional header to avoid duplicate blocks.
+* If the sequence of data to be appended is important, please use this API strictly in a single writer.
 * If you are guaranteed to have a single writer scenario, please look at options.absorbConditionalErrorsOnRetry and see if setting this flag to true is acceptable for you.
+* If the sequence of data to be appended is not important, this API can be used in parallel,
+* in this case, options.appendPosition can be left without settings.
 *
 * @this {BlobService}
 * @param {string}             container                                 The container name.