INSTALL.md: Fix inconsistent installation step numbering

[sreeshanth-soma]

Description

The Installation Steps section in INSTALL.md has inconsistent numbering.

Details

• Steps 3 and 4 are missing
• Step 6 is duplicated
• The sequence jumps (2 → 5 → 7 → 6)

The steps themselves are correct, but the numbering should be sequential to avoid confusion for new users.

Scope

• Documentation only
• No functional or behavioral changes

I can submit a small PR to fix the numbering if this is acceptable.