docs: fix incorrect inner doc comments

[wackbyte]

Replaces ///! with //!.

[codecov]

Codecov Report

Merging #534 (93219da) into main (5e92c70) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #534      +/-   ##
==========================================
- Coverage   84.38%   84.37%   -0.01%     
==========================================
  Files         275      275              
  Lines       31185    31185              
==========================================
- Hits        26315    26312       -3     
- Misses       4870     4873       +3     

Impacted Files	Coverage Δ
crates/mun_abi/src/primitive.rs	80.00% <ø> (ø)
crates/mun_codegen/src/value/mod.rs	62.80% <ø> (ø)
crates/mun_diagnostics/src/hir.rs	96.87% <ø> (ø)
crates/mun_syntax/src/parsing/event.rs	94.59% <ø> (ø)
crates/mun_target/src/abi/align.rs	92.00% <ø> (ø)
crates/mun_target/src/abi/integer.rs	0.00% <ø> (ø)
crates/mun_target/src/abi/mod.rs	65.18% <ø> (ø)
crates/mun_target/src/abi/size.rs	81.81% <ø> (ø)
crates/mun_vfs/src/monitor.rs	69.66% <ø> (ø)
crates/mun_compiler/src/lib.rs	62.92% <100.00%> (ø)
... and 1 more

... and 1 file with indirect coverage changes

[baszalmstra]

Thank you!