fix some typos in docs

[tqa236]

As discussed here, I fix several typos in docs in this PR.

@vaeng Hope you don't mind that I tagged you in this PR, as you replied in the forum. Some unfixed typos are listed below, please let me know if any is worth fixing.

Unfixed typos

./concepts/vector-arrays/introduction.md:40: speficic ==> specific
./concepts/vector-arrays/about.md:40: speficic ==> specific
./concepts/classes/introduction.md:28: Wizzard ==> Wizard
./concepts/classes/about.md:29: Wizzard ==> Wizard
./concepts/references/introduction.md:33: unitialized ==> uninitialized
./concepts/references/introduction.md:47: stil ==> still
./concepts/references/about.md:33: unitialized ==> uninitialized
./concepts/references/about.md:47: stil ==> still
./concepts/if-statements/introduction.md:44: accesed ==> accessed
./concepts/if-statements/about.md:44: accesed ==> accessed
./concepts/functions/introduction.md:25: definiton ==> definition
./concepts/functions/introduction.md:41: recommened ==> recommended, recommend
./concepts/functions/introduction.md:69: lenghth ==> length
./concepts/functions/about.md:25: definiton ==> definition
./concepts/functions/about.md:41: recommened ==> recommended, recommend
./concepts/functions/about.md:69: lenghth ==> length
./concepts/basics/introduction.md:36: adviseable ==> advisable
./concepts/basics/about.md:36: adviseable ==> advisable
./exercises/practice/crypto-square/crypto_square_test.cpp:44: thi ==> the, this
./exercises/practice/secret-handshake/.approaches/introduction.md:93: currrently ==> currently
./exercises/practice/anagram/anagram_test.cpp:123: patter ==> pattern
./exercises/practice/pangram/.approaches/introduction.md:83: currrently ==> currently
./exercises/concept/vehicle-purchase/vehicle_purchase_test.cpp:53: Bergamont ==> Bergamot
./exercises/concept/vehicle-purchase/vehicle_purchase_test.cpp:55: Bergamont ==> Bergamot
./exercises/concept/ellens-alien-game/ellens_alien_game_test.cpp:48: succesful ==> successful

[github-actions]

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[siebenschlaefer]

LGTM. Thank you!

[vaeng]

Thanks for the PR! LGTM