Addressed spelling issue.

.codespellexclude

@@ -13,3 +13,5 @@
     if (index < pFunc()->mErrors.size()) {
         issue = pFunc()->mIssues.at(pFunc()->mErrors.at(index));
     return pFunc()->mErrors.size();
+identity and expression, level of experience, education, socio-economic status,
+        "W3C MathML DTD error: Element apply content does not follow the DTD, expecting (csymbol | ci | cn | apply | reln | lambda | condition | declare | sep | semantics | annotation | annotation-xml | integers | reals | rationals | naturalnumbers | complexes | primes | exponentiale | imaginaryi | notanumber | true | false | emptyset | pi | eulergamma | infinity | interval | list | matrix | matrixrow | set | vector | piecewise | lowlimit | uplimit | bvar | degree | logbase | momentabout | domainofapplication | inverse | ident | domain | codomain | image | abs | conjugate | exp | factorial | arg | real | imaginary | floor | ceiling | not | ln | sin | cos | tan | sec | csc | cot | sinh | cosh | tanh | sech | csch | coth | arcsin | arccos | arctan | arccosh | arccot | arccoth | arccsc | arccsch | arcsec | arcsech | arcsinh | arctanh | determinant | transpose | card | quotient | divide | power | rem | implies | vectorproduct | scalarproduct | outerproduct | setdiff | fn | compose | plus | times | max | min | gcd | lcm | and | or | xor | union | intersect | cartesianproduct | mean | sdev | variance | median | mode | selector | root | minus | log | int | diff | partialdiff | divergence | grad | curl | laplacian | sum | product | limit | moment | exists | forall | neq | factorof | in | notin | notsubset | notprsubset | tendsto | eq | leq | lt | geq | gt | equivalent | approx | subset | prsubset | mi | mn | mo | mtext | ms | mspace | mrow | mfrac | msqrt | mroot | menclose | mstyle | merror | mpadded | mphantom | mfenced | msub | msup | msubsup | munder | mover | munderover | mmultiscripts | mtable | mtr | mlabeledtr | mtd | maligngroup | malignmark | maction)*, got (CDATA bvar ).",