Minor edits

Removed some capitalisation, small punctuation changes. Changed 'shell prompt' to 'terminal' for consistency with other resources
Minor edits/typo fixing
Minor edits/typo fixing
Minor edits/typo fixing
Typo/grammar fixes, house style
Typo/grammar fixes, other general edits

Headers now correctly formatted; for the avoidance of doubt, this is the newly-agreed house style for them.

Removed link to Wikipedia as there were multiple issues with the article and it is not immediately clear which section refers to CEA in the context of displays. Added a link to the heatsink on RS Components.
Minor edits/typo fixing
Minor fixes

Removed extra parenthesis; changed sdtv_mode and sdtv_aspect to house
style.
Resolve merge conflict