sql-faq: add missing DELAYED priority

[Oreoxmt]

What is changed, added or deleted? (Required)

Add the missing DELAYED priority

sql> SELECT HIGH_PRIORITY 1;
+---+
| 1 |
+---+
| 1 |
+---+
1 row in set (0.0014 sec)

sql> SELECT LOW_PRIORITY 1;
+---+
| 1 |
+---+
| 1 |
+---+
1 row in set (0.0004 sec)

sql> SELECT DELAYED 1;
+---+
| 1 |
+---+
| 1 |
+---+
1 row in set (0.0004 sec)

see also: https://github.com/pingcap/tidb/blob/1e0956d5ba41182e603295e02ae8f767d62979e4/distsql/request_builder.go#L257-L267

Which TiDB version(s) do your changes apply to? (Required)

Tips for choosing the affected version(s):

By default, CHOOSE MASTER ONLY so your changes will be applied to the next TiDB major or minor releases. If your PR involves a product feature behavior change or a compatibility change, CHOOSE THE AFFECTED RELEASE BRANCH(ES) AND MASTER.

For details, see tips for choosing the affected versions (in Chinese).

• master (the latest development version)
• v7.0 (TiDB 7.0 versions)
• v6.6 (TiDB 6.6 versions)
• v6.5 (TiDB 6.5 versions)
• v6.4 (TiDB 6.4 versions)
• v6.1 (TiDB 6.1 versions)
• v5.4 (TiDB 5.4 versions)
• v5.3 (TiDB 5.3 versions)
• v5.2 (TiDB 5.2 versions)
• v5.1 (TiDB 5.1 versions)
• v5.0 (TiDB 5.0 versions)

What is the related PR or file link(s)?

• This PR is translated from: sql-faq: add missing DELAYED priority docs#12237
• Other reference link(s):

Do your changes match any of the following descriptions?

• Delete files
• Change aliases
• Need modification after applied to another branch
• Might cause conflicts after applied to another branch

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• qiancai
• tiancaiamao

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[qiancai]

LGTM

[Oreoxmt]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 88e46cb

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.6: #13606.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.0: #13607.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.1: #13608.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.4: #13609.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.5: #13610.