docs: fix typos in Ketcher and Indigo release notes

[Avicennasis]

Summary

Fix 25 typos and grammar slips in the Ketcher and Indigo release-notes pages. Documentation only - no code, no functional changes.

rst/ketcher/release-notes/ketcher-2.16.0.md

• isotops -> isotopes
• greater then -> greater than
• When insert -> When inserting

rst/ketcher/release-notes/ketcher-3.7.0.md

• doesn't positioned -> isn't positioned
• peptides it they -> peptides if they

rst/ketcher/release-notes/ketcher-3.8.0.md

• enumerated form range -> enumerated from range
• event if it is eligable -> even if it is eligible
• Ketcher losts -> Ketcher loses
• created early that R1 -> created earlier than R1

rst/ketcher/release-notes/ketcher-3.0.0.md

• Indigo functions doesn't work -> Indigo functions don't work
• "intellisence"-like -> "IntelliSense"-like

rst/ketcher/release-notes/ketcher-2.22.0.md

• out or range -> out of range
• Snack of Flex modes -> Snake of Flex modes

rst/ketcher/release-notes/ketcher-3.2.0.md

• infinit -> infinite
• keboard -> keyboard
• antisence chain -> antisense chain
• antisense stand creation -> antisense strand creation
• sistuated -> situated, nubleotide -> nucleotide

rst/indigo/release-notes/indigo-1.18.0.md

• aminoacids -> amino acids
• access violationg -> access violation
• casue -> causes
• molecula -> molecule, fetures -> features
• stand alone H2 -> standalone H2
• wanishes -> vanishes
• Add/Rmove -> Add/Remove

Note for reviewers

These release-note bullets appear to be copied verbatim from the titles of the linked epam/ketcher and epam/Indigo issues, several of which contain the same typos upstream. The fixes here make the published documentation read correctly; the linked issue titles are untouched. If you prefer the notes to stay byte-identical to the issue titles, feel free to drop any individual line.

Every change was verified against the current master content before editing. No functional changes - documentation only.