[FLINK-18635][docs] Fix typo on website

[wangwangdaxian]

What is the purpose of the change

This PR fix typo in 'concepts/timely stream processing' part of the website.

Brief change log

• change Timely steam processing to Timely stream processing

Verifying this change

This change is a trivial rework / code cleanup without any test coverage.

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): no
• The public API, i.e., is any changed class annotated with @Public(Evolving): no
• The serializers: no
• The runtime per-record code paths (performance sensitive): no
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn/Mesos, ZooKeeper: no
• The S3 file system connector: no

Documentation

• Does this pull request introduce a new feature? no
• If yes, how is the feature documented? not applicable

[flinkbot]

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Automated Checks

Last check on commit c6fc00e (Sat Jul 18 17:57:14 UTC 2020)

Warnings:

• Documentation files were touched, but no .zh.md files: Update Chinese documentation or file Jira ticket.
• This pull request references an unassigned Jira ticket. According to the code contribution guide, tickets need to be assigned before starting with the implementation work.

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Review Progress

• ❓ 1. The [description] looks good.
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• ❓ 3. Needs [attention] from.
• ❓ 4. The change fits into the overall [architecture].
• ❓ 5. Overall code [quality] is good.

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[wangwangdaxian]

Hi,I'm a starter on contributing.At first,I was working on release-1.11 to fix this typo .
I see some suggestion that I should always make a contribution on master one minute later,
but I didnot find a way to change the from branch to the forked master.

Is it OK that I force pushed the forked master to the forked release-1.11 ?Or there is a better way?

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CI report:

• cb64874 Azure: SUCCESS

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[rmetzger]

Thanks a lot for your fix. I'll merge it to both master and release-1.11 branch.