Rollup merge of #63353 - ehuss:update-books, r=ehuss

Update books

## nomicon

1 commits in b7f0aba2f88a8feade70595efcfa3438e54e96c0..8a7d05615e5bc0a7fb961b4919c44f5221ee54da
2019-07-11 15:11:36 -0400 to 2019-08-07 07:46:59 -0500
- s/railguard/guardrail/ (rust-lang-nursery/nomicon#156)

## reference

5 commits in 8e7d614303b0dec7492e048e63855fcd3b944ec8..b4b3536839042a6743fc76f0d9ad2a812020aeaa
2019-07-16 21:02:33 +0100 to 2019-08-07 02:29:50 +0200
- Update partially initialized values in drop documentation. (rust-lang-nursery/reference#648)
- Define sound and unsound (rust-lang-nursery/reference#647)
- Fix a type in the modules section: functions => modules (rust-lang-nursery/reference#645)
- Fix some links. (rust-lang-nursery/reference#642)
- Update recursion_limit default limit (rust-lang-nursery/reference#633)

## rust-by-example

14 commits in e3679e214d8db44586aca9b20aa27517007d1923..f2c15ba5ee89ae9469a2cf60494977749901d764
2019-07-15 11:13:44 -0300 to 2019-08-07 10:14:25 -0300
- Remove redundant semicolons (rust-lang/rust-by-example#1239)
- Rename "Read Lines" chapter title (rust-lang/rust-by-example#1230)
- Added space between word and inline code block in unit_testing.md (rust-lang/rust-by-example#1237)
- [typo] fix unit_testing wrong output (rust-lang/rust-by-example#1210)
- flow_control/match/binding.md: `...' -> `..=' (rust-lang/rust-by-example#1233)
- generics/impl.md: follow rustfmt style (rust-lang/rust-by-example#1236)
- freeze.md: Incorrect example (rust-lang/rust-by-example#1226)
- Make `point` consistent (rust-lang/rust-by-example#1229)
- Fix typo at error -> panic (rust-lang/rust-by-example#1227)
- Snake didn't deserve to die 🐍 (rust-lang/rust-by-example#1228)
- Reorder links in destructuring.md (rust-lang/rust-by-example#1225)
- Rename variable names for consistent in iter_result.md (rust-lang/rust-by-example#1224)
- Fix several shell output and code highlights. (rust-lang/rust-by-example#1222)
- Add new example for Rc. (rust-lang/rust-by-example#1223)

## edition-guide

5 commits in f6c8b92d4e63edd28e862be952f33861f35956f8..e58bc4ca104e890ac56af846877c874c432a64b5
2019-07-06 22:10:32 +0200 to 2019-07-31 20:14:12 +0200
- Hide extraneous `use` in anonymous lifetime example. (rust-lang-nursery/edition-guide#190)
- Attempt to clarify "no more mod.rs". (rust-lang-nursery/edition-guide#187)
- Remove -preview for rustup components. (rust-lang-nursery/edition-guide#188)
- rust-lang-nursery/edition-guide#184 More clear explanation and Title. (rust-lang-nursery/edition-guide#185)
- More clear table headers (rust-lang-nursery/edition-guide#186)

## embedded-book

2 commits in ff334e74fdb9f197e621efa6d7c3105be892e888..c5da1e11915d3f28266168baaf55822f7e3fe999
2019-07-16 13:47:34 +0000 to 2019-08-05 23:02:10 +0000
- install/verify: fix next section link  (rust-embedded/book#202)
- Syst small fix  (rust-embedded/book#198)

edition-guide @ e58bc4ca

-Subproject commit f6c8b92d4e63edd28e862be952f33861f35956f8
+Subproject commit e58bc4ca104e890ac56af846877c874c432a64b5

embedded-book @ c5da1e11

-Subproject commit ff334e74fdb9f197e621efa6d7c3105be892e888
+Subproject commit c5da1e11915d3f28266168baaf55822f7e3fe999

nomicon @ 8a7d0561

-Subproject commit b7f0aba2f88a8feade70595efcfa3438e54e96c0
+Subproject commit 8a7d05615e5bc0a7fb961b4919c44f5221ee54da

reference @ b4b35368

-Subproject commit 8e7d614303b0dec7492e048e63855fcd3b944ec8
+Subproject commit b4b3536839042a6743fc76f0d9ad2a812020aeaa

rust-by-example @ f2c15ba5

-Subproject commit e3679e214d8db44586aca9b20aa27517007d1923
+Subproject commit f2c15ba5ee89ae9469a2cf60494977749901d764