docs: minor grammar & spelling fixes (#22851)

* docs: fix minor grammar error 'punctuations'

* docs: fix minor grammar error pluralizing Chromium

* docs: fix typo 'updateCurrentActiviy'

* docs: use consistent spelling of 'behavior'

* docs: use 'macOS' instead of 'Mac OS' or 'OS X'.

* docs: use 'GTK' instead of 'GTK+'

https://mail.gnome.org/archives/gtk-devel-list/2019-February/msg00000.html

* docs: minor capitalization: use 'TCP' not 'tcp'

* Update docs/development/build-instructions-linux.md

Co-Authored-By: Mark Lee <malept@users.noreply.github.com>

Co-authored-by: Mark Lee <malept@users.noreply.github.com>
Co-authored-by: John Kleinschmidt <jkleinsc@github.com>

docs/tutorial/installation.md

@@ -90,7 +90,7 @@ that cache folder to provide custom builds of Electron or to avoid making contac
 with the network at all.
 
 * Linux: `$XDG_CACHE_HOME` or `~/.cache/electron/`
-* MacOS: `~/Library/Caches/electron/`
+* macOS: `~/Library/Caches/electron/`
 * Windows: `$LOCALAPPDATA/electron/Cache` or `~/AppData/Local/electron/Cache/`
 
 On environments that have been using older versions of Electron, you might find the

docs/tutorial/macos-dock.md

@@ -1,4 +1,4 @@
-# MacOS Dock
+# macOS Dock
 
 Electron has APIs to configure the app's icon in the macOS Dock. A macOS-only
 API exists to create a custom dock menu, but

docs/tutorial/testing-widevine-cdm.md

@@ -49,7 +49,7 @@ The library file `widevinecdm.dll` will be under
 `Program Files(x86)/Google/Chrome/Application/CHROME_VERSION/WidevineCdm/_platform_specific/win_(x86|x64)/`
 directory.
 
-### On MacOS
+### On macOS
 
 The library file `libwidevinecdm.dylib` will be under
 `/Applications/Google Chrome.app/Contents/Versions/CHROME_VERSION/Google Chrome Framework.framework/Versions/A/Libraries/WidevineCdm/_platform_specific/mac_(x86|x64)/`