Docs-V1(UserGuide): Add root content in v1/User-Guide

[eeshaanSA]

What this PR does:

Add root files in UserGuide. Please check v0.55x userguide to check and review what has changed.

Why we need it:

Which issue(s) this PR fixes:

Fixes #

Does this PR introduce a user-facing change?:

• How are users affected by this change:
• Is this breaking change:
• How to migrate (if breaking change):

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 17.50%. Comparing base (c32694e) to head (927100b).

❗ There is a different number of reports uploaded between BASE (c32694e) and HEAD (927100b). Click for more details.

HEAD has 10 uploads less than BASE

Flag	BASE (c32694e)	HEAD (927100b)
.-pkg-app-pipedv1-plugin-waitapproval	1	0
.-pkg-plugin-sdk	1	0
.-tool-actions-plan-preview	1	0
.-pkg-app-pipedv1-plugin-scriptrun	1	0
.-pkg-app-pipedv1-plugin-analysis	1	0
.-pkg-app-pipedv1-plugin-wait	1	0
.-pkg-app-pipedv1-plugin-terraform	1	0
.-pkg-app-pipedv1-plugin-kubernetes	1	0
.	1	0
.-pkg-app-pipedv1-plugin-kubernetes_multicluster	1	0

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #6343       +/-   ##
===========================================
- Coverage   28.82%   17.50%   -11.33%     
===========================================
  Files         560        7      -553     
  Lines       59937      920    -59017     
===========================================
- Hits        17277      161    -17116     
+ Misses      41339      738    -40601     
+ Partials     1321       21     -1300     

Flag	Coverage Δ
.	?
.-pkg-app-pipedv1-plugin-analysis	?
.-pkg-app-pipedv1-plugin-kubernetes	?
.-pkg-app-pipedv1-plugin-kubernetes_multicluster	?
.-pkg-app-pipedv1-plugin-scriptrun	?
.-pkg-app-pipedv1-plugin-terraform	?
.-pkg-app-pipedv1-plugin-wait	?
.-pkg-app-pipedv1-plugin-waitapproval	?
.-pkg-plugin-sdk	?
.-tool-actions-gh-release	19.23% <ø> (ø)
.-tool-actions-plan-preview	?
.-tool-codegen-protoc-gen-auth	0.00% <ø> (ø)

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[eeshaanSA]

@khanhtc1202 I think at this point let us not focus on broken links. We will fix all of them once we have more clarity on v1 docs.

[khanhtc1202]

There is convention for directory name, the directory name should be snake case, instead of normal string (eg. managing-application) cc @eeshaanSA

[khanhtc1202]

#TODO:
Recheck this in pipedv1 cc @khanhtc1202