Rollup merge of rust-lang#35124 - steveklabnik:remove_style, r=aturon

Remove style guide.

We originally imported this into the repository with the intent of
fixing it up. Instead, nothing happened.

Its appearance on rust-lang.org makes it seem semi-official, but it's
not. The rustfmt strike team will end up producing something like this
anyway, and leaving it around does nothing but mislead people.

r? @aturon

Author: steveklabnik

mk/docs.mk

@@ -66,7 +66,7 @@ ERR_IDX_GEN_MD = $(RPATH_VAR2_T_$(CFG_BUILD)_H_$(CFG_BUILD)) $(ERR_IDX_GEN_EXE)
 
 D := $(S)src/doc
 
-DOC_TARGETS := book nomicon style error-index
+DOC_TARGETS := book nomicon error-index
 COMPILER_DOC_TARGETS :=
 DOC_L10N_TARGETS :=
 
@@ -209,13 +209,6 @@ doc/nomicon/index.html: $(RUSTBOOK_EXE) $(wildcard $(S)/src/doc/nomicon/*.md) |
 	$(Q)rm -rf doc/nomicon
 	$(Q)$(RUSTBOOK) build $(S)src/doc/nomicon doc/nomicon
 
-style: doc/style/index.html
-
-doc/style/index.html: $(RUSTBOOK_EXE) $(wildcard $(S)/src/doc/style/*.md) | doc/
-	@$(call E, rustbook: $@)
-	$(Q)rm -rf doc/style
-	$(Q)$(RUSTBOOK) build $(S)src/doc/style doc/style
-
 error-index: doc/error-index.html
 
 # Metadata used to generate the index is created as a side effect of