Fix Android CMake argument formatting in README

[eyesofish]

Issue #, if available:

N/A

Description of changes:

Remove shell backticks around -DTARGET_ARCH=ANDROID in the NMake and JOM commands. Backticks are command-substitution syntax rather than part of a CMake -D option, so the examples now pass the option literally as described.

Validation:

• Ran git diff --check.
• Confirmed the section contains two literal -DTARGET_ARCH=ANDROID arguments and no backtick-wrapped occurrences.

Generated with assistance from AI tools and reviewed by @eyesofish.

Check all that applies:

• Did a review by yourself.
• Added proper tests to cover this PR. (Not applicable: documentation-only command correction.)
• Checked if this PR is a breaking (APIs have been changed) change.
• Checked if this PR will not introduce cross-platform inconsistent behavior.
• Checked if this PR would require a ReadMe/Wiki update.

Check which platforms you have built SDK on to verify the correctness of this PR.

• Linux
• Windows
• Android
• MacOS
• IOS
• Other Platforms

No SDK build was required for this documentation-only correction.

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