Fix code style when missing the format type or text format

Author: ppcano

src/data/markdown/docs/01 guides/01 Getting started/02 Installation.md

@@ -23,7 +23,7 @@ sudo apt-get install k6
 > command due to firewalls or proxies blocking their requests. If you experience this issue, you may try this
 > alternative approach instead:
 >
-> ```
+> ```shell
 > wget -q -O - https://bintray.com/user/downloadSubjectPublicKey?username=bintray | sudo apt-key add -
 > ```
 

src/data/markdown/docs/01 guides/02 Using k6/13 Session recording - HAR support.md

@@ -137,7 +137,9 @@ You have two options to skip third-party requests in your k6 script.
 
 In Chrome, you can use the DevTools Network Filter to select only particular domains. The Filter input accepts a Regex to match multiple domains.
 
-    `/loadimpact.com|cloudfront.net/`
+```shell
+/loadimpact.com|cloudfront.net/
+```
 
 ![Save HAR filter domain using regex](./images/Session-recording-HAR-support/session_recorder_filter_domain.png)
 

src/data/markdown/docs/01 guides/02 Using k6/17 HTTP debugging.md

@@ -27,7 +27,7 @@ If we run it using `k6 run --http-debug script.js` we get output that looks like
 
 <div class="code-group" data-props='{"labels": [], "lineNumbers": [true]}'>
 
-```text
+```shell
           /\      |‾‾|  /‾‾/  /‾/
      /\  /  \     |  |_/  /  / /
     /  \/    \    |      |  /  ‾‾\

src/data/markdown/docs/01 guides/06 Misc/05 Archive.md

@@ -125,7 +125,7 @@ this:
 
 <div class="code-group" data-props='{"labels": ["Structure of archive.tar"], "lineNumbers": [true]}'>
 
-```text
+```shell
 ├-- data
 ├-- files
 |   └-- home

src/data/markdown/docs/03 cloud/02 Analyzing Results/11 Result Export.md

@@ -11,7 +11,7 @@ The CSV data has the following columns of data:
 
 <div class="code-group" data-props='{"labels": []}'>
 
-```
+```shell
 "time","metric","group_id","response_time","url","method","status","count","load_zone","tags"
 ```
 

src/data/markdown/docs/03 cloud/03 Integrations/04 Token.md

@@ -52,7 +52,7 @@ If you're a Google/GitHub Single Sign-On (SSO) user or if you have a use case wh
 
 <div class="code-group" data-props='{"labels": ["Using API token"]}'>
 
-```C
+```shell
 k6 login cloud --token YOUR_API_AUTH_TOKEN
 ```
 
@@ -68,15 +68,15 @@ You can also directly add your k6 cloud API authentication token to a configurat
 
 <div class="code-group" data-props='{"labels": ["Linux", "MacOS", "Windows"], "lineNumbers": [true, true, true]}'>
 
-```
+```shell
 ${HOME}/.config/loadimpact/k6/config.json
 ```
 
 ```
 ${HOME}/Library/Application Support/LoadImpact/k6/config.json
 ```
 
-```
+```shell
 C:\Users\&lt;User&gt;\AppData\Roaming\loadimpact\k6\config.json
 ```
 

src/data/markdown/docs/03 cloud/07 Cloud FAQ/12 Virtual Users.md

@@ -35,7 +35,7 @@ Calculating the number of virtual users can be done by using this formula:
 
 <div class="code-group" data-props='{"labels": ["Formula for calculating the number of VUs needed"]}'>
 
-```
+```shell
 VUs = (hourly sessions * average session duration in seconds)/3600
 ```