[clang-tidy] Update docs for clang-tidy checks. NFC

Changes mostly address formatting and unification of the style. Use
MarkDown style for inline code snippets and lists. Added some text
for a few checks.

The idea is to move most of the documentation out to separate rST files and have
implementation files refer to the corresponding documentation files.

llvm-svn: 246169
diff --git a/clang-tools-extra/clang-tidy/misc/InefficientAlgorithmCheck.h b/clang-tools-extra/clang-tidy/misc/InefficientAlgorithmCheck.h
index fd9edc4..6935b45 100644
--- a/clang-tools-extra/clang-tidy/misc/InefficientAlgorithmCheck.h
+++ b/clang-tools-extra/clang-tidy/misc/InefficientAlgorithmCheck.h
@@ -16,7 +16,7 @@
 namespace tidy {
 namespace misc {
 
-/// \brief Warns on inefficient use of STL algorithms on associative containers.
+/// Warns on inefficient use of STL algorithms on associative containers.
 ///
 /// Associative containers implements some of the algorithms as methods which
 /// should be preferred to the algorithms in the algorithm header. The methods