Additional replacements for installation docs

[guineveresaenger]

A few additional useful replaces encountered in the installation docs:

• terraform init --> pulumi up
• providers.tf --> Pulumi.yaml
• provider block --> provider configuration

[codecov]

Codecov Report

Attention: Patch coverage is 75.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 57.43%. Comparing base (9668009) to head (a905e76).
Report is 3 commits behind head on master.

Files with missing lines	Patch %	Lines
pkg/tfgen/installation_docs.go	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2431      +/-   ##
==========================================
- Coverage   57.44%   57.43%   -0.02%     
==========================================
  Files         369      369              
  Lines       50189    50193       +4     
==========================================
- Hits        28831    28826       -5     
- Misses      19779    19788       +9     
  Partials     1579     1579              

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[pulumi-bot]

This PR has been shipped in release v3.91.1.