rustup-{set,self,completions,doc,override,component}: add page (#10729)

* rustup set: add page

* rustup self: add page

* rustup completions: add page

* rustup doc: add page

* rustup override: add page

* rustup component: add page

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Co-authored-by: K.B.Dharun Krishna <kbdharunkrishna@gmail.com>

pages/common/rustup-override.md

@@ -0,0 +1,21 @@
+# rustup override
+
+> Modify directory toolchain overrides.
+> See `rustup help toolchain` for more information about toolchains.
+> More information: <https://rust-lang.github.io/rustup>.
+
+- List directiory toolchain overrides:
+
+`rustup override list`
+
+- Set the override toolchain for the current directory (i.e. tell `rustup` to run `cargo`, `rustc`, etc. from a specific toolchain when in that directory):
+
+`rustup override set {{toolchain}}`
+
+- Remove the toolchain override for the current directory:
+
+`rustup override unset`
+
+- Remove all toolchain overrides for directories that no longer exist:
+
+`rustup override unset --nonexistent`