Update instructions on how to join the Slack channel

[HaoYang670]

Signed-off-by: remzi 13716567376yh@gmail.com

Which issue does this PR close?

Closes #2192.

Rationale for this change

What changes are included in this PR?

Are there any user-facing changes?

[codecov-commenter]

Codecov Report

Merging #2219 (01e1fbf) into master (acd8042) will decrease coverage by 0.00%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2219      +/-   ##
==========================================
- Coverage   82.53%   82.52%   -0.01%     
==========================================
  Files         239      239              
  Lines       62299    62304       +5     
==========================================
+ Hits        51417    51419       +2     
- Misses      10882    10885       +3     

Impacted Files	Coverage Δ
...rquet/src/arrow/record_reader/definition_levels.rs	88.60% <0.00%> (-0.43%)	⬇️
parquet_derive/src/parquet_field.rs	65.53% <0.00%> (-0.23%)	⬇️
parquet/src/encodings/encoding.rs	93.43% <0.00%> (-0.20%)	⬇️
.../src/array/builder/primitive_dictionary_builder.rs	80.30% <0.00%> (+1.61%)	⬆️

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[alamb]

Thanks @HaoYang670 -- looks like there is a markdown formatting CI check that failed, but otherwise 👍

[alamb]

@HaoYang670 try this link: https://discord.gg/YAb2TdazKQ

[HaoYang670]

https://discord.gg/YAb2TdazKQ
This works! 😁 I will update the link

[ursabot]

Benchmark runs are scheduled for baseline = 588f408 and contender = 393f006. 393f006 is a master commit associated with this PR. Results will be available as each benchmark for each run completes.
Conbench compare runs links:
[Skipped ⚠️ Benchmarking of arrow-rs-commits is not supported on ec2-t3-xlarge-us-east-2] ec2-t3-xlarge-us-east-2
[Skipped ⚠️ Benchmarking of arrow-rs-commits is not supported on test-mac-arm] test-mac-arm
[Skipped ⚠️ Benchmarking of arrow-rs-commits is not supported on ursa-i9-9960x] ursa-i9-9960x
[Skipped ⚠️ Benchmarking of arrow-rs-commits is not supported on ursa-thinkcentre-m75q] ursa-thinkcentre-m75q
Buildkite builds:
Supported benchmarks:
ec2-t3-xlarge-us-east-2: Supported benchmark langs: Python, R. Runs only benchmarks with cloud = True
test-mac-arm: Supported benchmark langs: C++, Python, R
ursa-i9-9960x: Supported benchmark langs: Python, R, JavaScript
ursa-thinkcentre-m75q: Supported benchmark langs: C++, Java