Update books

## nomicon

1 commits in bbf06ad39d1f45654047e9596b750cc6e6d1b693..adca786547d08fe676b2fc7a6f08c2ed5280ca38
2021-01-22 07:07:31 -0800 to 2021-02-16 16:34:20 +0900
- Merge pull request rust-lang/nomicon#254 from mdaverde/ml/adds-compiler-err-lifetimes

## reference

9 commits in f02b09eb6e8af340ad1256a54adb7aae2ff3163e..361367c126290ac17cb4089f8d38fd8b2ac43f98
2021-01-22 01:53:02 -0800 to 2021-02-15 09:58:13 -0800
- Define turbofish in the glossary (rust-lang/reference#964)
- Remove enum variant expr (rust-lang/reference#963)
- One sentence is one line src/expressions/* (rust-lang/reference#962)
- Referencify bool type (rust-lang/reference#940)
- Fix typo in type cast expression table (rust-lang/reference#959)
- Define rust (rust-lang/reference#953)
- Remove "Memory Ownership" chapter (rust-lang/reference#952)
- Added setting nightly as a requirement for running tests (rust-lang/reference#955)
- Refactored build steps for better readability (rust-lang/reference#936)

## book

13 commits in e724bd826580ff95df48a8533af7dec1080693d4..db5e8a5105aa22979490dce30e33b68d8645761d
2021-01-20 08:19:49 -0600 to 2021-02-12 16:58:20 -0500
- Update to Rust 1.50
- Fix issue rust-lang/book#2574 - Improve the explanation about the behaviour of `read_line`. (rust-lang/book#2575)
- closures: replace "is called" with "is defined" (rust-lang/book#2556)
- Minor clarification: types -> values in ch16-04 (rust-lang/book#2587)
- fixed hidden code listing (rust-lang/book#2610)
- Merge remote-tracking branch 'origin/pr/2604'
-  (rust-lang/book#2601)
- Merge remote-tracking branch 'origin/pr/2589'
- Fix text wrapping
- Some small rewordings I noticed while rereading just now
-  (rust-lang/book#2592)
- Removed 'of' between type alias in Ch 19-04. (rust-lang/book#2581)
- Merge remote-tracking branch 'origin/pr/2554'

## rust-by-example

2 commits in f633769acef68574427a6fae6c06f13bc2199573..551cc4bc8394feccea6acd21f86d9a4e1d2271a0
2021-01-13 20:58:25 -0300 to 2021-02-03 17:12:37 -0300
- remove // (rust-lang/rust-by-example#1409)
- Update arc.md (rust-lang/rust-by-example#1406)

## edition-guide

3 commits in b91a9a881ee007c12e74e844460ec407cf07a50f..1da3c411f17adb1ba5de1683bb6acee83362b54a
2020-11-02 11:02:03 -0600 to 2021-02-16 16:46:40 -0800
- Update link for no_std. (rust-lang/edition-guide#231)
- Add git link to the source. (rust-lang/edition-guide#228)
- Update musl libc link (rust-lang/edition-guide#230)

## embedded-book

1 commits in ceec19e873be87c6ee5666b030c6bb612f889a96..4cf7981696a85c3e633076c6401611bd3f6346c4
2021-01-03 13:13:10 +0000 to 2021-02-11 10:55:22 +0000
- Fix installing dateutil since it is now a dependency of the GHP import script  (rust-embedded/book#282)