docs: fix lite client formatting (#3198)

Closes #3180

lite/doc.go

@@ -15,9 +15,7 @@ for you, so you can just build nice applications.
 We design for clients who have no strong trust relationship with any Tendermint
 node, just the blockchain and validator set as a whole.
 
-# Data structures
-
-## SignedHeader
+SignedHeader
 
 SignedHeader is a block header along with a commit -- enough validator
 precommit-vote signatures to prove its validity (> 2/3 of the voting power)
@@ -42,7 +40,7 @@ The FullCommit is also declared in this package as a convenience structure,
 which includes the SignedHeader along with the full current and next
 ValidatorSets.
 
-## Verifier
+Verifier
 
 A Verifier validates a new SignedHeader given the currently known state. There
 are two different types of Verifiers provided.
@@ -56,35 +54,32 @@ greater).
 DynamicVerifier - this Verifier implements an auto-update and persistence
 strategy to verify any SignedHeader of the blockchain.
 
-## Provider and PersistentProvider
+Provider and PersistentProvider
 
 A Provider allows us to store and retrieve the FullCommits.
 
-```go
-type Provider interface {
-	// LatestFullCommit returns the latest commit with
-	// minHeight <= height <= maxHeight.
-	// If maxHeight is zero, returns the latest where
-	// minHeight <= height.
-	LatestFullCommit(chainID string, minHeight, maxHeight int64) (FullCommit, error)
-}
-```
+    type Provider interface {
+        // LatestFullCommit returns the latest commit with
+        // minHeight <= height <= maxHeight.
+        // If maxHeight is zero, returns the latest where
+        // minHeight <= height.
+        LatestFullCommit(chainID string, minHeight, maxHeight int64) (FullCommit, error)
+    }
 
 * client.NewHTTPProvider - query Tendermint rpc.
 
 A PersistentProvider is a Provider that also allows for saving state.  This is
 used by the DynamicVerifier for persistence.
 
-```go
-type PersistentProvider interface {
-	Provider
+    type PersistentProvider interface {
+        Provider
 
-	// SaveFullCommit saves a FullCommit (without verification).
-	SaveFullCommit(fc FullCommit) error
-}
-```
+        // SaveFullCommit saves a FullCommit (without verification).
+        SaveFullCommit(fc FullCommit) error
+    }
 
 * DBProvider - persistence provider for use with any libs/DB.
+
 * MultiProvider - combine multiple providers.
 
 The suggested use for local light clients is client.NewHTTPProvider(...) for
@@ -93,7 +88,7 @@ dbm.NewMemDB()), NewDBProvider("label", db.NewFileDB(...))) to store confirmed
 full commits (Trusted)
 
 
-# How We Track Validators
+How We Track Validators
 
 Unless you want to blindly trust the node you talk with, you need to trace
 every response back to a hash in a block header and validate the commit