BYOH agent documentation

[Madhur97]

What this PR does / why we need it:
This PR adds BYO host agent documentation in docs. This will be used to add all agent related information.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #622

[anusha94]

Super useful doc!
Minor nits - otherwise lgtm

[anusha94]

@Madhur97 Your CLA is not verified. Since you are a VMware employee, you can be a member of the vmware-tanzu org. Ping the team for help on this.

[codecov-commenter]

Codecov Report

Merging #611 (8f9b359) into main (45d0b6a) will increase coverage by 1.23%.
The diff coverage is n/a.

❗ Current head 8f9b359 differs from pull request most recent head 2510a5a. Consider uploading reports for the commit 2510a5a to get more accurate results

@@            Coverage Diff             @@
##             main     #611      +/-   ##
==========================================
+ Coverage   67.75%   68.99%   +1.23%     
==========================================
  Files          26       19       -7     
  Lines        2388     1964     -424     
==========================================
- Hits         1618     1355     -263     
+ Misses        662      497     -165     
- Partials      108      112       +4     

Impacted Files	Coverage Δ
.../installer/internal/algo/output_builder_counter.go
agent/installer/os_detector.go
agent/installer/registry.go
agent/installer/internal/algo/apt_step.go
agent/installer/internal/algo/shell_step.go
.../installer/internal/algo/mock_ubuntu_with_error.go
agent/installer/checks.go
agent/installer/installer.go
agent/installer/internal/algo/ubuntu20_4K8s1_22.go
agent/installer/internal/algo/installer.go
... and 11 more

[shamsher31]

Thanks. LGTM 👍

[dharmjit]

LGTM, and as @anusha94 mentioned this is very useful.