[DOCS]: wrong lines highlighted in code example for programming environment

[shahzebsiddiqui]

Documentation Link

https://buildtest.readthedocs.io/en/devel/configuring_buildtest/compilers.html#enable-programming-environments

Issue Description

issue with highlighting code

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[shahzebsiddiqui]

@Xiangs18 if you have chance could you please fix this in the docs. We need to highlight the lines compilers, enable_prgenv and everything under prgenv_modules